TESS

The Transiting Exoplanet Survey Satellite

TESS is a NASA Explorer mission launched in 2018 to study exoplanets, or planets orbiting stars outside our solar system. TESS will discover thousands of exoplanets in orbit around the brightest stars in the sky. It will monitor more than 200,000 stars, looking for temporary dips in brightness caused by planets transiting across these stars. This first-ever spaceborne all-sky transit survey will identify a wide range of planets, from Earth-sized to gas giants. The mission will find exoplanet candidates for follow-up observation from missions like the James Webb Space Telescope, which will determine whether these candidates could support life.


For more information, please visit the TESS website.

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Produced Videos

  • Swift, TESS Catch Eruptions from an Active Galaxy
    2021.01.12
    Using data from facilities including NASA’s Neil Gehrels Swift Observatory and Transiting Exoplanet Survey Satellite (TESS), scientists have studied 20 instances and counting of regular outbursts of an event called ASASSN-14ko. Astronomers classify galaxies with unusually bright and variable centers as active galaxies. These objects can produce much more energy than the combined contribution of all their stars, including higher-than-expected levels of visible, ultraviolet, and X-ray light. Astrophysicists think the extra emission comes from near the galaxy’s central supermassive black hole, where a swirling disk of gas and dust accumulates and heats up because of gravitational and frictional forces. The black hole slowly consumes the material, which creates random fluctuation in the disk’s emitted light. But astronomers are interested in finding active galaxies with flares that happen at regular intervals, which might help them identify and study new phenomena and events. ASASSN-14ko was first detected on Nov. 14, 2014, by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes. It occurred in ESO 253-3, an active galaxy over 570 million light-years away in the southern constellation Pictor. At the time, astronomers thought the outburst was most likely a supernova, a one-time event that destroys a star. Six years later, scientists examined the ESO 253-3 ASAS-SN light curve, or the graph of its brightness over time, and noticed a series of evenly spaced flares – a total of 17, all separated by 114 days. Each flare reaches its peak brightness in about five days, then steadily dims. They predicted that the galaxy would flare again on May 17, 2020, so they coordinated joint observations with ground- and space-based facilities, including multiwavelength measurements with Swift. ASASSN-14ko erupted right on schedule. Subsequent flares were predicted and observed on Sept. 7 and Dec. 20. Using measurements of these and previous flares from ASAS-SN, TESS, Swift and other observatories, including NASA’s NuSTAR and the European Space Agency’s XMM-Newton, scientists propose the repeating flares are most likely a partial tidal disruption event. A tidal disruption event occurs when an unlucky star strays too close to a black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around the black hole. Astronomers see bright flares from these events when the shed gas strikes the black hole’s accretion disk. In this case, the astronomers suggest that one of the galaxy’s supermassive black holes, one with about 78 million times the Sun’s mass, partially disrupts an orbiting giant star. The star's orbit isn’t circular, and each time it passes closest to the black hole, it bulges outward, shedding mass but not completely breaking apart. Every encounter strips away an amount of gas equal to about three times the mass of Jupiter.
  • TESS's Northern Sky Vista
    2020.10.05
    Familiar stars shine, nebulae glow, and nearby galaxies tantalize in a new panorama of the northern sky assembled from 208 images from NASA’s Transiting Exoplanet Survey Satellite (TESS). Within this starry scene, TESS has discovered several new exoplanets, and more than 600 candidates awaiting confirmation. The northern mosaic covers less of the sky than its southern counterpart, which was imaged during the mission’s first year of operations. For about half of the northern sectors, the team decided to angle the cameras further north to minimize the impact of scattered light from Earth and the Moon. This results in an obvious gap along the mosaic’s outer edge. TESS has now begun its extended mission, during which it will spend another year imaging the southern sky. The satellite will revisit planets discovered in its first year, discover new worlds, and fill in coverage gaps from its initial survey. Improvements to the satellite’s data collection and processing now allow TESS to return full sector images every 10 minutes and measure the brightness of thousands of stars every 20 seconds – all while continuing its previous strategy of measuring the brightness of tens of thousands of stars every two minutes.
  • Join the Hunt for New Worlds Through Planet Patrol
    2020.09.30
    Help NASA find exoplanets, worlds beyond our solar system, through a newly launched website called Planet Patrol. This citizen science platform allows members of the public to collaborate with professional astronomers as they sort through a stockpile of star-studded images collected by NASA’s Transiting Exoplanet Survey Satellite (TESS).

    TESS uses its four cameras to take full images of one patch of sky, called a sector, every 10 minutes for a month at a time. This long stare allows TESS to see when planets pass in front of their stars, or transit, and dim their light. Over the course of a year, TESS collects hundreds of thousands of snapshots, each containing thousands of possible planets – too many for scientists to examine without help.

    Computers are very good at analyzing such data sets, but they’re not perfect. Even the most carefully crafted algorithms can fail when the signal from a planet is weak. Some of the most interesting exoplanets, like small worlds with long orbits, can be especially challenging. Planet Patrol volunteers will help discover such worlds and will contribute to scientists’ understanding of how planetary systems form and evolve throughout the universe.

    Planets aren’t the only source of changes in starlight, though. Some stars naturally change brightness over time, for example. In other cases, a star could actually be an eclipsing binary, where two orbiting stars alternately transit or eclipse each other. Or there may be an eclipsing binary in the background that creates the illusion of a planet transiting a target star. Instrumental quirks can also cause brightness variations. All these false alarms can trick automated planet-hunting processes.

    On the new website, participants will help astronomers sift through TESS images of potential planets by answering a set of questions for each – like whether it contains multiple bright sources or if it resembles stray light rather than light from a star. These questions help the researchers narrow down the list of possible planets for further follow-up study.

  • NASA’s TESS Provides New Insights Into an Ultrahot World
    2020.06.30
    Measurements from NASA’s Transiting Exoplanet Survey Satellite (TESS) have enabled astronomers to greatly improve their understanding of the bizarre environment of KELT-9 b, one of the hottest planets known. Located about 670 light-years away in the constellation Cygnus, KELT-9 b was discovered in 2017 because the planet passed in front of its star for a part of each orbit, an event called a transit. Transits regularly dim the star’s light by a small but detectable amount. Between July 18 and Sept. 11, 2019, as part of the mission's yearlong campaign to observe the northern sky, TESS observed 27 transits of KELT-9 b, and these observations allowed the team to model the system’s unusual star and its impact on the planet. KELT-9 b is a gas giant world about 1.8 times bigger than Jupiter, with 2.9 times its mass. Tidal forces have locked its rotation so the same side always faces its star. The planet swings around its star in just 36 hours on an orbit that carries it almost directly above both of the star's poles. The close orbit means the planet's dayside temperature is around 7,800 degrees Fahrenheit (4,300 C), hotter than the surfaces of some stars. This intense heating also causes the planet’s atmosphere to stream away into space. Its odd host star is about twice the size of the Sun and averages about 56 percent hotter. But it spins 38 times faster than the Sun, completing a full rotation in just 16 hours. Its rapid spin distorts the star’s shape, flattening it at the poles and widening its midsection. This causes the star’s poles to heat up and brighten while its equatorial region cools and dims, a phenomenon called gravity darkening. The result is a temperature difference across the star’s surface of almost 1,500 F (800 C). With each orbit, KELT-9 b twice experiences the full range of stellar temperatures, producing what amounts to a peculiar seasonal sequence. The planet experiences “summer” when it swings over each hot pole and “winter” when it passes over the star’s cooler midsection. So KELT-9 b experiences two summers and two winters every year, with each season about nine hours. KELT-9 b begins its transit near the star's bright poles and then blocks less and less light as it travels over the star's dimmer equator. This asymmetry provides clues to the temperature and brightness changes across the star’s surface, and they permitted the team to reconstruct the star’s out-of-round shape, how it’s oriented in space, its range of surface temperatures, and other factors impacting the planet.
  • TESS, Spitzer Missions Discover a Unique Young World
    2020.06.24
    For more than a decade, astronomers have searched for planets orbiting AU Microscopii, a nearby star still surrounded by a disk of debris left over from its formation. Now scientists using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope report the discovery of a planet about as large as Neptune that circles the young star in just over a week. The system, known as AU Mic for short, provides a one-of-kind laboratory for studying how planets and their atmospheres form, evolve and interact with their stars. AU Mic is a M-type red dwarf star at least 150 times younger than our Sun. It’s so young that a vast disk of dust and icy grains still surrounds it. The planet, AU Mic b, orbits very close to its star within a central zone where the disk material is cleared away. It's around 8% larger than Neptune, with no more than about 3.4 times its mass.
  • TESS Satellite Discovered Its First World Orbiting Two Stars
    2020.01.06
    Researchers working with data from NASA’s Transiting Exoplanet Survey Satellite (TESS) have discovered the mission’s first circumbinary planet, a world orbiting two stars. The planet, called TOI 1338 b, is around 6.9 times larger than Earth, or between the sizes of Neptune and Saturn. It lies in a system 1,300 light-years away in the constellation Pictor. The stars in the system make an eclipsing binary, which occurs when the stellar companions circle each other in our plane of view. One is about 10% more massive than our Sun, while the other is cooler, dimmer and only one-third the Sun’s mass. TOI 1338 b’s transits are irregular, between every 93 and 95 days, and vary in depth and duration thanks to the orbital motion of its stars. TESS only sees the transits crossing the larger star — the transits of the smaller star are too faint to detect. Although the planet transits irregularly, its orbit is stable for at least the next 10 million years. The orbit’s angle to us, however, changes enough that the planet transit will cease after November 2023 and resume eight years later.
  • TESS Mission’s First Earth-size World in Star’s Habitable-zone
    2020.01.06
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations. TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40% of the Sun’s mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets. The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight. The Spitzer data increased scientists’ confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system. While the exact conditions on TOI 700 d are unknown, scientists used current information, like the planet’s size and the type of star it orbits, and modeled 20 potential environments for TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability. One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side. Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, where winds flow away from the night side of the planet and converge on the point directly facing the star.
  • TESS's Southern Sky Panorama
    2019.11.05
    The glow of the Milky Way — our galaxy seen edgewise — arcs across a sea of stars in a new mosaic of the southern sky produced from a year of observations by NASA’s Transiting Exoplanet Survey Satellite (TESS). Constructed from 208 TESS images taken during the mission’s first year of science operations, completed on July 18, the southern panorama reveals both the beauty of the cosmic landscape and the reach of TESS's cameras. Within this scene, TESS has discovered 29 exoplanets, or worlds beyond our solar system, and more than 1,000 candidate planets astronomers are now investigating. TESS divided the southern sky into 13 sectors and imaged each one of them for nearly a month using four cameras, which carry a total of 16 charge-coupled devices (CCDs). Remarkably, the TESS cameras capture a full sector of the sky every 30 minutes as part of its search for exoplanet transits. Transits occur when a planet passes in front of its host star from our perspective, briefly and regularly dimming its light. During the satellite’s first year of operations, each of its CCDs captured 15,347 30-minute science images. These images are just a part of more than 20 terabytes of southern sky data TESS has returned, comparable to streaming nearly 6,000 high-definition movies. In addition to its planet discoveries, TESS has imaged a comet in our solar system, followed the progress of numerous stellar explosions called supernovae, and even caught the flare from a star ripped apart by a supermassive black hole. After completing its southern survey, TESS turned north to begin a year-long study of the northern sky.
  • TESS Catches Its First Star-destroying Black Hole
    2019.09.26
    NASA’s planet-hunting Transiting Exoplanet Survey Satellite (TESS) watched a black hole tear apart a star from start to finish, a cataclysmic phenomenon called a tidal disruption event. The blast, named ASASSN-19bt, was found on Jan. 29 by the All-Sky Automated Survey for Supernovae (ASAS-SN), a worldwide network of 20 robotic telescopes. Shortly after the discovery, ASAS-SN requested follow-up observations by NASA’s Swift satellite, ESA’s (European Space Agency’s) XMM-Newton and ground-based 1-meter telescopes in the global Las Cumbres Observatory network. The disruption occurred in TESS’s continuous viewing zone, which is always in sight of one of the satellite’s four cameras. This allowed astronomers to view the explosion from beginning to end.
  • TESS Discovery Leads to Surprising Find of Promising World
    2019.07.31
    A planet discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) has pointed the way to additional worlds orbiting the same star, one of which is located in the star’s habitable zone. If made of rock, this planet may be around twice Earth’s size. The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet — a world beyond our solar system — that passes across the face of its star during every orbit and briefly dims the star’s light. The transits TESS observed belong to GJ 357 b, a planet about 22% larger than Earth. It orbits 11 times closer to its star than Mercury does our Sun. But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is especially intriguing. The planet’s size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth’s size. GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun. If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface. GJ 357 c, the middle planet, has a mass at least 3.4 times Earth’s, orbits the star every 9.1 days at a distance a bit more than twice that of GJ 357 b. TESS did not observe transits from this planet, which suggests its orbit is slightly tilted — perhaps by less than 1 degree — relative to the hot Earth’s orbit, so it never passes across the star from our perspective.
  • Highlights From TESS's First Year
    2019.07.25
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered 21 planets outside our solar system and captured data on other interesting events occurring in the southern sky during its first year of science. TESS has now turned its attention to the northern hemisphere to complete the most comprehensive planet-hunting expedition ever undertaken. TESS began hunting for exoplanets (or worlds orbiting distant stars) in the southern sky in July of 2018, while also collecting data on supernovae, black holes and other phenomena in its line of sight. Along with the planets TESS has discovered, the mission has identified over 800 candidate exoplanets that are waiting for confirmation by ground-based telescopes. To search for exoplanets, TESS uses four large cameras to watch a 24-by-96-degree section of the sky for 27 days at a time. Some of these sections overlap, so some parts of the sky are observed for almost a year. TESS is concentrating on stars closer than 300 light-years from our solar system, watching for transits, which are periodic dips in brightness caused by an object, like a planet, passing in front of the star. On July 18, the southern portion of the survey was completed and the spacecraft turned its cameras to the north. When it completes the northern section in 2020, TESS will have mapped over three quarters of the sky. Here are a few of the interesting objects and events TESS saw during its first year.
  • TESS Discovers Its Tiniest World To Date
    2019.06.27
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered a world between the sizes of Mars and Earth orbiting a bright, cool, nearby star. The planet, called L 98-59b, marks the smallest found by TESS yet. Two other worlds orbit the same star. While all three planets’ sizes are known, further study with other telescopes will be needed to determine if they have atmospheres and, if so, which gases are present. The L 98-59 worlds nearly double the number of small exoplanets — that is, planets beyond our solar system — that have the best potential for this kind of follow-up. L 98-59b is around 80% Earth’s size and about 10% smaller than the previous record holder discovered by TESS. Its host star, L 98-59, is an M dwarf about one-third the mass of the Sun and lies about 35 light-years away in the southern constellation Volans. While L 98-59b is a record for TESS, even smaller planets have been discovered in data collected by NASA’s Kepler satellite, including Kepler-37b, which is only 20% larger than the Moon. The two other worlds in the system, L 98-59c and L 98-59d, are respectively around 1.4 and 1.6 times Earth’s size. All three were discovered by TESS using transits, periodic dips in the star’s brightness caused when each planet passes in front of it.
  • Going Interstellar with TESS and Kepler
    2019.03.27
    For the longest time, space seemed like just a big, nearly empty place. However, as we learned more about the universe around us, we discovered other planets orbiting our Sun, and even planets that orbit other stars trillions of miles away. In this video, discover how NASA has explored the space beyond Earth and our solar system with spacecraft like Voyagers 1 and 2, and how we’ve discovered thousands of planets outside of our solar system — also called exoplanets — with space telescopes like Kepler and TESS.

    Credit: NASA's Goddard Space Flight Center

    Music: "Virtual Memory" from Killer Tracks

    YouTube link

    Complete transcript available.

    Watch this video on the NASA Goddard YouTube channel.

  • NASA's Planet-Hunting TESS Catches a Comet Before Starting Science
    2018.08.06
    Before NASA’s Transiting Exoplanet Survey Satellite (TESS) started science operations on July 25, 2018, the planet hunter sent back a stunning sequence of serendipitous images showing the motion of a comet. Taken over the course of 17 hours on July 25, these TESS images helped demonstrate the satellite’s ability to collect a prolonged set of stable periodic images covering a broad region of the sky — all critical factors in finding transiting planets orbiting nearby stars. Over the course of these tests, TESS took images of C/2018 N1, a comet discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) satellite on June 29. The comet, located about 29 million miles (48 million kilometers) from Earth in the southern constellation Piscis Austrinus, is seen to move across the frame from right to left as it orbits the Sun. The comet’s tail, which consists of gases carried away from the comet by an outflow from the Sun called the solar wind, extends to the top of the frame and gradually pivots as the comet glides across the field of view. In addition to the comet, the images reveal a treasure trove of other astronomical activity. The stars appear to shift between white and black as a result of image processing. The shift also highlights variable stars — which change brightness either as a result of pulsation, rapid rotation, or by eclipsing binary neighbors. Asteroids in our solar system appear as small white dots moving across the field of view. Towards the end of the video, one can see a faint broad arc of light moving across the middle section of the frame from left to right. This is stray light from Mars, which is located outside the frame. The images were taken when Mars was at its brightest near opposition, or its closest distance, to Earth. These images were taken during a short period near the end of the mission’s commissioning phase, prior to the start of science operations. The movie presents just a small fraction of TESS’s active field of view. The team continues to fine-tune the spacecraft’s performance as it searches for distant worlds. TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory in Lexington, Massachusetts; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.
  • TESS Shorts
    2018.04.03
    NASA's Transiting Exoplanet Survey Satellite - TESS will fly a never-before-used orbit that completes two circuits around the Earth every time the Moon orbits. This special orbit will allow TESS’s cameras to monitor each patch of sky continuously from nearly a month at a time. To get into this orbit, TESS will make a series of loops culminating in a lunar gravitational-assist, which will give it the push it needs. TESS will reach its orbit about 60 days after launch.
  • TESS Undergoes Integration and Testing
    2018.02.08
    The Transiting Exoplanet Survey Satellite (TESS) is the next step in the search for planets outside of our solar system, including those that could support life. The mission will find exoplanets that periodically block part of the light from their host stars, events called transits. TESS will survey 200,000 of the brightest stars near the sun to search for transiting exoplanets. The mission is scheduled to launch March 20, 2018, and no later than June 2018.
  • TESS Fly Your Exoplanet
    2017.04.03
    The Transiting Exoplanet Survey Satellite (TESS) is taking your art to space! Draw a picture of an exoplanet, or planet orbiting another star, that you think TESS could find. It could fly on the TESS spacecraft, launching in 2018! Download the form at https://tess.gsfc.nasa.gov/fly_your_exoplanet.html and send us your drawing today! Deadline for submissions is November 20, 2017.
  • TESS Mission Trailer
    2015.03.20
    This video introduces the Transiting Exoplanet Survey Satellite (TESS). This is a joint mission between NASA and MIT that will scan the entire sky searching for exoplanets, or planets outside our Solar System. Using four state-of-the-art cameras, TESS will monitor over 500,000 stars, looking for changes in their brightness that signal a planet crossing over. The stars TESS looks at will be 30-100 times brighter than those observed by the Kepler satellite, making follow-up observations much easier. Using TESS data, missions like the James Webb Space Telescope can determine specific characteristics of these planets, including whether they could support life. TESS is scheduled to launch in 2017.

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  • Swift, TESS Catch Eruptions from an Active Galaxy
    2021.01.12
    Using data from facilities including NASA’s Neil Gehrels Swift Observatory and Transiting Exoplanet Survey Satellite (TESS), scientists have studied 20 instances and counting of regular outbursts of an event called ASASSN-14ko. Astronomers classify galaxies with unusually bright and variable centers as active galaxies. These objects can produce much more energy than the combined contribution of all their stars, including higher-than-expected levels of visible, ultraviolet, and X-ray light. Astrophysicists think the extra emission comes from near the galaxy’s central supermassive black hole, where a swirling disk of gas and dust accumulates and heats up because of gravitational and frictional forces. The black hole slowly consumes the material, which creates random fluctuation in the disk’s emitted light. But astronomers are interested in finding active galaxies with flares that happen at regular intervals, which might help them identify and study new phenomena and events. ASASSN-14ko was first detected on Nov. 14, 2014, by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes. It occurred in ESO 253-3, an active galaxy over 570 million light-years away in the southern constellation Pictor. At the time, astronomers thought the outburst was most likely a supernova, a one-time event that destroys a star. Six years later, scientists examined the ESO 253-3 ASAS-SN light curve, or the graph of its brightness over time, and noticed a series of evenly spaced flares – a total of 17, all separated by 114 days. Each flare reaches its peak brightness in about five days, then steadily dims. They predicted that the galaxy would flare again on May 17, 2020, so they coordinated joint observations with ground- and space-based facilities, including multiwavelength measurements with Swift. ASASSN-14ko erupted right on schedule. Subsequent flares were predicted and observed on Sept. 7 and Dec. 20. Using measurements of these and previous flares from ASAS-SN, TESS, Swift and other observatories, including NASA’s NuSTAR and the European Space Agency’s XMM-Newton, scientists propose the repeating flares are most likely a partial tidal disruption event. A tidal disruption event occurs when an unlucky star strays too close to a black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around the black hole. Astronomers see bright flares from these events when the shed gas strikes the black hole’s accretion disk. In this case, the astronomers suggest that one of the galaxy’s supermassive black holes, one with about 78 million times the Sun’s mass, partially disrupts an orbiting giant star. The star's orbit isn’t circular, and each time it passes closest to the black hole, it bulges outward, shedding mass but not completely breaking apart. Every encounter strips away an amount of gas equal to about three times the mass of Jupiter.
  • Potential Giant World Circles a Tiny Star
    2020.09.16
    An international team of astronomers has reported what may be the first example of an intact planet closely orbiting a white dwarf, a dense leftover of a Sun-like star that’s only 40% bigger than Earth. The detection of the Jupiter-size body was made using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope.

    The object, called WD 1856 b, is about seven times larger than the white dwarf. Based on the object’s size, astronomers think it’s a giant gaseous planet, which future observations and research may confirm. They also estimate it’s no more than 14 times Jupiter’s mass. The potential world circles the white dwarf every 34 hours, over 60 times faster than Mercury orbits our Sun.

    The system may have looked very different prior to 6 billion years ago, though. When a Sun-like star runs out of fuel, it swells up to hundreds to thousands of times its original size, forming a cooler red giant star. Eventually it ejects its outer layers of gas, losing up to 80% of its mass. The remaining hot core becomes a white dwarf. Any nearby objects are engulfed and incinerated during this process, which in this system would have included WD 1856 b in its current orbit. Astronomers estimate the possible planet must have originated at least 50 times farther away.

    The team suggests several scenarios that could have nudged WD 1856 b onto an elliptical path around the white dwarf. This trajectory would have become more circular over time as the star’s gravity stretched the object, creating enormous tides that dissipated its orbital energy.

  • NASA’s TESS Provides New Insights Into an Ultrahot World
    2020.06.30
    Measurements from NASA’s Transiting Exoplanet Survey Satellite (TESS) have enabled astronomers to greatly improve their understanding of the bizarre environment of KELT-9 b, one of the hottest planets known. Located about 670 light-years away in the constellation Cygnus, KELT-9 b was discovered in 2017 because the planet passed in front of its star for a part of each orbit, an event called a transit. Transits regularly dim the star’s light by a small but detectable amount. Between July 18 and Sept. 11, 2019, as part of the mission's yearlong campaign to observe the northern sky, TESS observed 27 transits of KELT-9 b, and these observations allowed the team to model the system’s unusual star and its impact on the planet. KELT-9 b is a gas giant world about 1.8 times bigger than Jupiter, with 2.9 times its mass. Tidal forces have locked its rotation so the same side always faces its star. The planet swings around its star in just 36 hours on an orbit that carries it almost directly above both of the star's poles. The close orbit means the planet's dayside temperature is around 7,800 degrees Fahrenheit (4,300 C), hotter than the surfaces of some stars. This intense heating also causes the planet’s atmosphere to stream away into space. Its odd host star is about twice the size of the Sun and averages about 56 percent hotter. But it spins 38 times faster than the Sun, completing a full rotation in just 16 hours. Its rapid spin distorts the star’s shape, flattening it at the poles and widening its midsection. This causes the star’s poles to heat up and brighten while its equatorial region cools and dims, a phenomenon called gravity darkening. The result is a temperature difference across the star’s surface of almost 1,500 F (800 C). With each orbit, KELT-9 b twice experiences the full range of stellar temperatures, producing what amounts to a peculiar seasonal sequence. The planet experiences “summer” when it swings over each hot pole and “winter” when it passes over the star’s cooler midsection. So KELT-9 b experiences two summers and two winters every year, with each season about nine hours. KELT-9 b begins its transit near the star's bright poles and then blocks less and less light as it travels over the star's dimmer equator. This asymmetry provides clues to the temperature and brightness changes across the star’s surface, and they permitted the team to reconstruct the star’s out-of-round shape, how it’s oriented in space, its range of surface temperatures, and other factors impacting the planet.
  • TESS, Spitzer Missions Discover a Unique Young World
    2020.06.24
    For more than a decade, astronomers have searched for planets orbiting AU Microscopii, a nearby star still surrounded by a disk of debris left over from its formation. Now scientists using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope report the discovery of a planet about as large as Neptune that circles the young star in just over a week. The system, known as AU Mic for short, provides a one-of-kind laboratory for studying how planets and their atmospheres form, evolve and interact with their stars. AU Mic is a M-type red dwarf star at least 150 times younger than our Sun. It’s so young that a vast disk of dust and icy grains still surrounds it. The planet, AU Mic b, orbits very close to its star within a central zone where the disk material is cleared away. It's around 8% larger than Neptune, with no more than about 3.4 times its mass.
  • TESS Aids Breakthrough in Puzzling Stellar Flashes
    2020.05.13
    Astronomers have detected elusive pulsation patterns in dozens of young, rapidly rotating stars thanks to data from NASA's Transiting Exoplanet Survey Satellite (TESS). The discovery will revolutionize scientists' ability to study details like the ages, sizes and compositions of these stars — all members of a class named for the prototype, the bright star Delta Scuti. Geologists studying seismic waves from earthquakes figured out Earth's internal structure from the way the reverberations changed speed and direction as they traveled through it. Astronomers apply the same principle to study the interiors of stars through their pulsations, a field called asteroseismology. Sound waves travel through a star's interior at speeds that change with depth, and they all combine into pulsation patterns at the star's surface. Astronomers can detect these patterns as tiny fluctuations in brightness and use them to determine the star's age, temperature, composition, internal structures and other properties. But scientists have had trouble interpreting Delta Scuti pulsations. These stars generally rotate once or twice a day, at least a dozen times faster than the Sun. The rapid rotation flattens the stars at the poles and jumbles the pulsation patterns, making them more complicated and difficult to decipher. Using new data from TESS and archived information from ground observatories and NASA's now-retired Kepler space telescope, astrophysicists identified a batch of 60 Delta Scuti stars with clear patterns for the first time.
  • TESS Mission’s First Earth-size World in Star’s Habitable-zone
    2020.01.06
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations. TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40% of the Sun’s mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets. The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight. The Spitzer data increased scientists’ confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system. While the exact conditions on TOI 700 d are unknown, scientists used current information, like the planet’s size and the type of star it orbits, and modeled 20 potential environments for TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability. One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side. Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, where winds flow away from the night side of the planet and converge on the point directly facing the star.
  • TESS Satellite Discovered Its First World Orbiting Two Stars
    2020.01.06
    Researchers working with data from NASA’s Transiting Exoplanet Survey Satellite (TESS) have discovered the mission’s first circumbinary planet, a world orbiting two stars. The planet, called TOI 1338 b, is around 6.9 times larger than Earth, or between the sizes of Neptune and Saturn. It lies in a system 1,300 light-years away in the constellation Pictor. The stars in the system make an eclipsing binary, which occurs when the stellar companions circle each other in our plane of view. One is about 10% more massive than our Sun, while the other is cooler, dimmer and only one-third the Sun’s mass. TOI 1338 b’s transits are irregular, between every 93 and 95 days, and vary in depth and duration thanks to the orbital motion of its stars. TESS only sees the transits crossing the larger star — the transits of the smaller star are too faint to detect. Although the planet transits irregularly, its orbit is stable for at least the next 10 million years. The orbit’s angle to us, however, changes enough that the planet transit will cease after November 2023 and resume eight years later.
  • TESS Shows Ancient North Star Has Eclipses
    2020.01.06
    Astronomers using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) have shown that Alpha Draconis, a well-studied star visible to the naked eye, and its fainter companion star regularly eclipse each other. While astronomers previously knew this was a binary system, the mutual eclipses came as a complete surprise. The eclipses are brief, lasting only six hours, so ground-based observations can easily miss them. The system ranks among the brightest-known eclipsing binaries where the two stars are widely separated, or detached, and only interact gravitationally. Such systems are important because astronomers can measure the masses and sizes of both stars with unrivaled accuracy. Alpha Draconis, also known as Thuban, lies about 270 light-years away in the northern constellation Draco. Despite its “alpha” designation, it shines as Draco’s fourth-brightest star. Thuban’s fame arises from a historical role it played some 4,700 years ago, back when the earliest pyramids were being built in Egypt. At that time, it appeared as the North Star, the one closest to the northern pole of Earth’s spin axis, the point around which all of the other stars appear to turn in their nightly motion. Today, this role is played by Polaris, a brighter star in the constellation Ursa Minor. The change happened because Earth’s spin axis performs a cyclic 26,000-year wobble, called precession, that slowly alters the sky position of the rotational pole. Discovering eclipses in a well-known, bright, historically important star highlights how TESS impacts the broader astronomical community. In this case, the high precision, uninterrupted TESS data can be used to help constrain fundamental stellar parameters at a level we’ve never before achieved.
  • TESS Catches Its First Star-destroying Black Hole
    2019.09.26
    NASA’s planet-hunting Transiting Exoplanet Survey Satellite (TESS) watched a black hole tear apart a star from start to finish, a cataclysmic phenomenon called a tidal disruption event. The blast, named ASASSN-19bt, was found on Jan. 29 by the All-Sky Automated Survey for Supernovae (ASAS-SN), a worldwide network of 20 robotic telescopes. Shortly after the discovery, ASAS-SN requested follow-up observations by NASA’s Swift satellite, ESA’s (European Space Agency’s) XMM-Newton and ground-based 1-meter telescopes in the global Las Cumbres Observatory network. The disruption occurred in TESS’s continuous viewing zone, which is always in sight of one of the satellite’s four cameras. This allowed astronomers to view the explosion from beginning to end.
  • TESS Discovery Leads to Surprising Find of Promising World
    2019.07.31
    A planet discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) has pointed the way to additional worlds orbiting the same star, one of which is located in the star’s habitable zone. If made of rock, this planet may be around twice Earth’s size. The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet — a world beyond our solar system — that passes across the face of its star during every orbit and briefly dims the star’s light. The transits TESS observed belong to GJ 357 b, a planet about 22% larger than Earth. It orbits 11 times closer to its star than Mercury does our Sun. But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is especially intriguing. The planet’s size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth’s size. GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun. If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface. GJ 357 c, the middle planet, has a mass at least 3.4 times Earth’s, orbits the star every 9.1 days at a distance a bit more than twice that of GJ 357 b. TESS did not observe transits from this planet, which suggests its orbit is slightly tilted — perhaps by less than 1 degree — relative to the hot Earth’s orbit, so it never passes across the star from our perspective.
  • Kepler Passes Planet-Finding Torch to TESS Animation
    2018.10.30
    After nine years in space, NASA's Kepler has reached its end. The Kepler and K2 missions have discovered over 2,600 confirmed exoplanets so far, including some in the habitable zones of their stars. Kepler used transits--regular dips in a star's brightness caused by orbiting planets--to find new worlds. It's the same method used by NASA's Transiting Exoplanet Survey Satellite. In a way, Kepler has passed the planet-finding torch on to TESS, which will scan nearly the entire sky to continue the hunt for exoplanets.
  • TESS Spacecraft Animations
    2018.01.08
    The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat.
  • TESS Coverage Animations
    2018.03.28
    Animation showing the TESS spacecraft and the coverage of its four cameras. Each camera covers a 24 degrees-square patch of sky and the four cameras are arranged in a vertical strip called an observation sector.
  • TESS-Kepler Field-of-View Animation
    2018.03.28
    This animation begins with Kepler's first observation zone and the constellation Cygnus. It adds a single TESS camera field for comparison, and then pulls back to show all four TESS camera fields--called an observation sector--and the amount of sky they cover. The sphere of the sky unwraps into a flat projection and all the regions observed by Kepler appear. TESS's full 2 year coverage appears, starting in the southern hemisphere and ending in the northern. Finally, the map is rewrapped into a sphere.

    Credit: NASA/JPL-Caltech/T. Pyle (IPAC)

  • TESS Social Media Products
    2018.04.03
    Looping gif of the TESS spacecraft
  • TESS Beauty Pass Animation
    2016.09.20
    Beauty pass of the TESS satellite.
  • TESS Rounds Up its First Planets, Snares Far-flung Supernovae
    2019.01.07
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has found three confirmed exoplanets, or worlds beyond our solar system, in its first three months of observations. The mission’s sensitive cameras also captured 100 short-lived changes — most of them likely stellar outbursts — in the same region of the sky. They include six supernova explosions whose brightening light was recorded by TESS even before the outbursts were discovered by ground-based telescopes. The new discoveries show that TESS is delivering on its goal of discovering planets around nearby bright stars. Using ground-based telescopes, astronomers are now conducting follow-up observations on more than 280 TESS exoplanet candidates. The first confirmed discovery is a world called Pi Mensae c about twice Earth’s size. Every six days, the new planet orbits the star Pi Mensae, located about 60 light-years away and visible to the unaided eye in the southern constellation Mensa. The bright star Pi Mensae is similar to the Sun in mass and size. Next is LHS 3884b, a rocky planet about 1.3 times Earth’s size located about 49 light-years away in the constellation Indus, making it among the closest transiting exoplanets known. The star is a cool M-type dwarf star about one-fifth the size of our Sun. Completing an orbit every 11 hours, the planet lies so close to its star that some of its rocky surface on the daytime side may form pools of molten lava. The third — and possibly fourth — planets orbit HD 21749, a K-type star about 80 percent the Sun’s mass and located 53 light-years away in the southern constellation Reticulum. The confirmed planet, HD 21749b, is about three times Earth’s size and 23 times its mass, orbits every 36 days, and has a surface temperature around 300 degrees Fahrenheit (150 degrees Celsius). It is the longest-period transiting planet within 100 light-years of the solar system, and it has the coolest surface temperature of a transiting exoplanet around a star brighter than 10th magnitude, or about 25 times fainter than the limit of unaided human vision. What’s even more exciting are hints the system holds a second candidate planet about the size of Earth that orbits the star every eight days. If confirmed, it could be the smallest TESS planet to date. In its primary two-year mission, TESS will observe nearly the whole sky, providing a rich catalog of worlds around nearby stars. Their proximity to Earth will enable detailed characterization of the planets through follow-up observations from space- and ground-based telescopes. But in its month-long stare into each sector, TESS records many additional phenomena, including comets, asteroids, flare stars, eclipsing binaries, white dwarf stars and supernovae, resulting in an astronomical treasure trove. In the first TESS sector alone, observed between July 25 and Aug. 22, 2018, the mission caught dozens of short-lived, or transient, events, including images of six supernovae in distant galaxies that were later seen by ground-based telescopes. These early observations hold the key to understanding a class of supernovae that serve as an important yardstick for cosmological studies. Type Ia supernovae form through two channels. One involves the merger of two orbiting white dwarfs, compact remnants of stars like the Sun. The other occurs in systems where a white dwarf draws gas from a normal star, gradually gaining mass until it becomes unstable and explodes. Astronomers don’t know which scenario is more common, but TESS could detect modifications to the early light of the explosion caused by the presence of stellar companion.
  • Exoplanet HD 21749 c Animation
    2019.08.07
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size world, named HD 21749 c. It’s about 89% of Earth’s size and orbits HD 21749, a K-type star with about 70% of the Sun’s mass located 53 light-years away in the southern constellation Reticulum, and is the second planet TESS has identified in the system. The new world is likely rocky and circles very close to its star, completing one orbit in just under eight days. The planet’s surface is likely very hot, with temperatures perhaps as high as 800 F (427 C). HD 21749 c's host star is bright and relatively nearby, and is therefore well suited to more detailed follow-up studies, which could provide critical information about the planet’s properties.
  • Animations of TESS's First Exoplanets
    2019.09.02
    Illustration of the exoplanet LHS 3844 b. It is a rocky planet about 1.3 times Earth’s size located about 49 light-years away in the constellation Indus, making it among the closest transiting exoplanets known. The star is a cool M-type dwarf star about one-fifth the size of our Sun. Completing an orbit every 11 hours, the planet lies so close to its star that some of its rocky surface on the daytime side may form pools of molten lava.

    Credit: NASA/MIT/TESS

Raw footage/B-roll

  • TESS Launch Footage
    2018.04.26
    NASA’s Transiting Exoplanet Survey Satellite (TESS) was launched April 18 on a SpaceX Falcon 9 rocket, from Cape Canaveral Air Force Station in Florida. TESS is NASA’s next mission to search for planets outside of our solar system, known as exoplanets, including those that could support life. The mission is expected to catalog thousands of planet candidates and vastly increase the current number of known exoplanets. TESS will find the most promising exoplanets orbiting relatively nearby stars, giving future researchers a rich set of new targets for more comprehensive follow-up studies, including the potential to assess their capacity to harbor life.
  • TESS Arrives at KSC
    2018.03.05
    NASA's next planet-hunting mission has arrived in Floriday to begin preparation for launch. The Transiting Exoplanet Survey Satellite (TESS) will launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station in Florida this spring. TESS was delivered Feb. 12 aboard a truck from Orbital ATK in Dulles, Virginia, where it was assembled and tested in 2017. Over the next month, the spacecraft will be prepped for launch at Kennedy's Payload Hazardous Servicing Facility. TESS is the next step in NASA's search for planets outside our solar system, known as exoplanets.
  • TESS Solar Array Deploy
    2018.03.13
    NASA's next planet-hunting mission is at the Kennedy Space Center in Florida to begin preparation for launch. The Transiting Exoplanet Survey Satellite (TESS) will launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station in Florida this spring. TESS is being prepped for launch at Kennedy's Payload Hazardous Servicing Facility. TESS is the next step in NASA's search for planets outside our solar system, known as exoplanets.
  • TESS Spacecraft Beauty Shots
    2017.11.20
    The fully integrated Transiting Exoplanet Survey Satellite (TESS), which will launch in 2018 to find thousands of new planets orbiting other stars.
  • TESS Integration Prep B-Roll
    2017.05.18
    The TESS spacecraft being prepared for integration of the TESS instrument at Orbital ATK.
  • TESS Camera Mounting Timelapse
    2017.08.03
    The four TESS cameras being mounted to the camera plate in preparation for integration to spacecraft at Orbital ATK in Dulles, Va.
  • TESS Camera Mounting Photos
    2017.08.03
    TESS cameras being mounted to the camera plate at Orbital ATK in Dulles, Va. before installation onto the spacecraft.
  • TESS Camera Integration Photos
    2017.09.11
    The TESS cameras being integrated onto the spacecraft at Orbital ATK in Dulles, Va.
  • TESS Camera Integration B-Roll
    2017.09.13
    Footage of TESS cameras being integrated onto spacecraft at Orbital ATK in Dulles, Va.
  • TESS Solar Array Deployment Photos
    2017.10.26
    Photos of the TESS solar arrays being deployed at Orbital ATK in Dulles, Va. before the assembled spacecraft is moved into testing.
  • TESS Vibration Testing Photos
    2017.10.26
    Photos of TESS spacecraft being tested on vibration table at Orbital ATK in Dulles, Va.
  • TESS Solar Array Deployment B-Roll
    2017.10.27
    Video Footage of the TESS spacecraft solar arrays being deployed for testing at Orbital ATK in Dulles, Va.

Still images

  • NASA’s TESS Finds New Worlds in a River of Stars
    2021.02.12
    Using observations from NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a trio of hot worlds larger than Earth orbiting a much younger version of our Sun called TOI 451. The system resides in the recently discovered Pisces-Eridanus stream, a collection of stars less than 3% the age of our solar system that stretches across one-third of the sky. The planets were discovered in TESS images taken between October and December 2018. Follow-up studies of TOI 451 and its planets included observations made in 2019 and 2020 using NASA’s Spitzer Space Telescope, which has since been retired, as well as many ground-based facilities. Archival infrared data from NASA’s Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) satellite – collected between 2009 and 2011 under its previous moniker, WISE – suggests the system retains a cool disk of dust and rocky debris. Other observations show that TOI 451 likely has two distant stellar companions circling each other far beyond the planets. The young star TOI 451, better known to astronomers as CD-38 1467, lies about 400 light-years away in the constellation Eridanus. It has 95% of our Sun’s mass, but it is 12% smaller, slightly cooler, and emits 35% less energy. TOI 451 rotates every 5.1 days, which is more than five times faster than the Sun. Even TOI 451’s most distant planet orbits three times closer than Mercury ever approaches to the Sun, so all of these worlds are quite hot and inhospitable to life as we know it. Temperature estimates range from about 2,200 degrees Fahrenheit (1,200 degrees Celsius) for the innermost planet to about 840 F (450 C) for the outermost one. TOI 451 b orbits every 1.9 days, is about 1.9 times Earth’s size, and its estimated mass ranges from two to 12 times Earth’s. The next planet out, TOI 451 c, completes an orbit every 9.2 days, is about three times larger than Earth, and holds between three and 16 times Earth’s mass. The farthest and largest world, TOI 451 d, circles the star every 16 days, is four times the size of our planet, and weighs between four and 19 Earth masses. Astronomers expect planets as big as these to retain much of their atmospheres despite the intense heat from their nearby star. Different theories of how atmospheres evolve by the time a planetary system reaches TOI 451’s age predict a wide range of properties. Observing starlight passing through the atmospheres of these planets provides an opportunity to study this phase of development and could aid in constraining current models. Stellar streams form when the gravity of our Milky Way galaxy tears apart star clusters or dwarf galaxies. The individual stars move out along the cluster’s original orbit, forming an elongated group that gradually disperses. In 2019, a team led by Stefan Meingast at the University of Vienna used data from the European Space Agency’s Gaia mission to discover the Pisces-Eridanus stream, named for the constellations containing the greatest concentrations of stars. Stretching across 14 constellations, the stream is about 1,300 light-years long. However, the age initially determined for the stream was much older than we now think. Later in 2019, researchers led by Jason Curtis at Columbia University in New York City analyzed TESS data for dozens of stream members. Younger stars spin faster than their older counterparts do, and they also tend to have prominent starspots – darker, cooler regions like sunspots. As these spots rotate in and out of our view, they can produce slight variations in a star’s brightness that TESS can measure. The TESS measurements revealed overwhelming evidence of starspots and rapid rotation among the stream’s stars. Based on this result, Curtis and his colleagues found that the stream was only 120 million years old – similar to the famous Pleiades cluster and eight times younger than previous estimates. The mass, youth, and proximity of the Pisces-Eridanus stream make it an exciting fundamental laboratory for studying star and planet formation and evolution.
  • TESS Northern and Southern Mosaics
    2020.10.05
    NASA's Transiting Exoplanet Survey Satellite (TESS) completed its two-year-long primary mission, during which it imaged about 75% of the sky, in July 2020. The southern panorama was completed in July 2019, while imaging for the northern survey took place over the following year. For about half of the northern sectors, the TESS team decided to angle the cameras further north to minimize the impact of scattered light from Earth and the Moon, resulting in a prominent gap in sky coverage.
  • TESS's Northern Sky Vista
    2020.10.05
    Familiar stars shine, nebulae glow, and nearby galaxies tantalize in a new panorama of the northern sky assembled from 208 images from NASA’s Transiting Exoplanet Survey Satellite (TESS). Within this starry scene, TESS has discovered several new exoplanets, and more than 600 candidates awaiting confirmation. The northern mosaic covers less of the sky than its southern counterpart, which was imaged during the mission’s first year of operations. For about half of the northern sectors, the team decided to angle the cameras further north to minimize the impact of scattered light from Earth and the Moon. This results in an obvious gap along the mosaic’s outer edge. TESS has now begun its extended mission, during which it will spend another year imaging the southern sky. The satellite will revisit planets discovered in its first year, discover new worlds, and fill in coverage gaps from its initial survey. Improvements to the satellite’s data collection and processing now allow TESS to return full sector images every 10 minutes and measure the brightness of thousands of stars every 20 seconds – all while continuing its previous strategy of measuring the brightness of tens of thousands of stars every two minutes.
  • TESS's Southern Sky Panorama
    2019.11.05
    The glow of the Milky Way — our galaxy seen edgewise — arcs across a sea of stars in a new mosaic of the southern sky produced from a year of observations by NASA’s Transiting Exoplanet Survey Satellite (TESS). Constructed from 208 TESS images taken during the mission’s first year of science operations, completed on July 18, the southern panorama reveals both the beauty of the cosmic landscape and the reach of TESS's cameras. Within this scene, TESS has discovered 29 exoplanets, or worlds beyond our solar system, and more than 1,000 candidate planets astronomers are now investigating. TESS divided the southern sky into 13 sectors and imaged each one of them for nearly a month using four cameras, which carry a total of 16 charge-coupled devices (CCDs). Remarkably, the TESS cameras capture a full sector of the sky every 30 minutes as part of its search for exoplanet transits. Transits occur when a planet passes in front of its host star from our perspective, briefly and regularly dimming its light. During the satellite’s first year of operations, each of its CCDs captured 15,347 30-minute science images. These images are just a part of more than 20 terabytes of southern sky data TESS has returned, comparable to streaming nearly 6,000 high-definition movies. In addition to its planet discoveries, TESS has imaged a comet in our solar system, followed the progress of numerous stellar explosions called supernovae, and even caught the flare from a star ripped apart by a supermassive black hole. After completing its southern survey, TESS turned north to begin a year-long study of the northern sky.
  • TESS Southern Hemisphere Sector Images
    2019.11.05
    NASA’s newest planet hunter, the Transiting Exoplanet Survey Satellite (TESS), is now providing valuable data to help scientists discover and study exciting new exoplanets, or planets beyond our solar system. Part of the treasure trove from TESS’s first year of science operations includes wide-field pictures of the southern sky. The images show each of the 13 southern sky sectors TESS monitored. TESS acquired the images using four cameras; black lines in the images are gaps between camera detectors. Some stars are so bright they saturate an entire column of pixels on the detectors, creating long spikes of light. TESS’s cameras, designed and built by the Massachusetts Institute of Technology’s Lincoln Laboratory and the MIT Kavli Institute, monitor enormous 24-by-96-degree swaths of the sky to look for transiting planets. These events occur when a planet passes in front of its star as viewed from the satellite’s perspective, causing a regular dip in the star’s brightness. After two years, TESS will have monitored 26 sectors for 27 days each, covering 85 percent of the sky. On July 18, 2019, TESS completed monitoring the last of its 13 southern sectors, then turned its cameras to the north to carry out a second year-long survey.
  • NASA’s TESS Finds Three New Worlds
    2019.07.29
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered three new worlds -- one slightly larger than Earth and two of a type not found in our solar system orbiting a nearby star. The planets straddle an observed gap in the sizes of known planets and promise to be among the most curious targets for future studies. TESS Object of Interest (TOI) 270 is a faint, cool star more commonly identified by its catalog name: UCAC4 191-004642. The M-type dwarf star is about 40% smaller than the Sun in both size and mass, and it has a surface temperature about one-third cooler than the Sun’s. The planetary system lies about 73 light-years away in the southern constellation of Pictor. The innermost planet, TOI 270 b, is likely a rocky world about 25% larger than Earth. It orbits the star every 3.4 days at a distance about 14 times closer than Mercury orbits the Sun. Based on statistical studies of known exoplanets of similar size, the science team estimates TOI 270 b has a mass around 1.9 times greater than Earth’s. The other two planets, TOI 270 c and d, are, respectively, 2.4 and 2.1 times larger than Earth and orbit the star every 5.7 and 11.4 days. Although only about half its size, both may be similar to Neptune in our solar system, with compositions dominated by gases rather than rock, and they likely weigh around 7 and 5 times Earth’s mass, respectively. All of the planets are expected to be tidally locked to the star, which means they only rotate once every orbit and keep the same side facing the star at all times, just as the Moon does in its orbit around Earth. Planet c and d might best be described as mini-Neptunes, a type of planet not seen in our own solar system. The researchers hope further exploration of TOI 270 may help explain how two of these mini-Neptunes formed alongside a nearly Earth-size world.
  • NASA’s TESS Releases First Science Image
    2018.09.17
    NASA’s newest planet hunter, the Transiting Exoplanet Survey Satellite (TESS), is now providing valuable data to help scientists discover and study exciting new exoplanets, or planets beyond our solar system. Part of the data from TESS’s initial science orbit includes a detailed picture of the southern sky taken with all four of the spacecraft’s wide-field cameras. This “first light” science image captures a wealth of stars and other objects, including systems previously known to have exoplanets. TESS acquired the image using all four cameras during a 30-minute period on Tuesday, Aug. 7. The black lines in the image are gaps between the camera detectors. The small bright dot above the Small Magellanic Cloud is a globular cluster — a spherical collection of hundreds of thousands of stars — called NGC 104, also known as 47 Tucanae because of its location in the southern constellation Tucana, the Toucan. Two stars, Beta Gruis and R Doradus, are so bright they saturate an entire column of pixels on the detectors of TESS’s second and fourth cameras, creating long spikes of light. TESS’s cameras, designed and built by MIT’s Lincoln Laboratory in Lexington, Massachusetts, and the MIT Kavli Institute, monitor large swaths of the sky to look for transits. Transits occur when a planet passes in front of its star as viewed from the satellite’s perspective, causing a regular dip in the star’s brightness. TESS will spend two years monitoring 26 such sectors for 27 days each, covering 85 percent of the sky. During its first year of operations, the satellite will study the 13 sectors making up the southern sky. Then TESS will turn to the 13 sectors of the northern sky to carry out a second year-long survey.
  • TESS Artist Concept Images
    2017.09.22
    Artist concept images of the Transiting Exoplanet Survey Satellite.
  • TESS Spacecraft Beauty Shots
    2017.11.20
    The fully integrated Transiting Exoplanet Survey Satellite (TESS), which will launch in 2018 to find thousands of new planets orbiting other stars.

Presentation Resources

  • Exoplanet Transit Animations
    2018.08.06
    When a planet passes directly between a star and its observer, it dims the star's light by a measurable amount. This animation shows a single planet and the corresponding light curve.
  • Exoplanet Animations
    2016.09.20
    Animation imagining what an ice-covered exoplanet might look like.
  • HD 189733b Exoplanet Animation
    2012.06.28
    The exoplanet HD 189733b lies so near its star that it completes an orbit every 2.2 days. In late 2011, NASA's Hubble Space Telescope found that the planet's upper atmosphere was streaming away at speeds exceeding 300,000 mph. Just before the Hubble observation, NASA's Swift detected the star blasting out a strong X-ray flare, one powerful enough to blow away part of the planet's atmosphere.
  • Exoplanet scale
    2017.01.13
    This illustration compares the sizes of various exoplanets with Earth and the Moon.

    Credit: NASA's Goddard Space Flight Center

  • TESS Rounds Up its First Planets, Snares Far-flung Supernovae
    2019.01.07
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has found three confirmed exoplanets, or worlds beyond our solar system, in its first three months of observations. The mission’s sensitive cameras also captured 100 short-lived changes — most of them likely stellar outbursts — in the same region of the sky. They include six supernova explosions whose brightening light was recorded by TESS even before the outbursts were discovered by ground-based telescopes. The new discoveries show that TESS is delivering on its goal of discovering planets around nearby bright stars. Using ground-based telescopes, astronomers are now conducting follow-up observations on more than 280 TESS exoplanet candidates. The first confirmed discovery is a world called Pi Mensae c about twice Earth’s size. Every six days, the new planet orbits the star Pi Mensae, located about 60 light-years away and visible to the unaided eye in the southern constellation Mensa. The bright star Pi Mensae is similar to the Sun in mass and size. Next is LHS 3884b, a rocky planet about 1.3 times Earth’s size located about 49 light-years away in the constellation Indus, making it among the closest transiting exoplanets known. The star is a cool M-type dwarf star about one-fifth the size of our Sun. Completing an orbit every 11 hours, the planet lies so close to its star that some of its rocky surface on the daytime side may form pools of molten lava. The third — and possibly fourth — planets orbit HD 21749, a K-type star about 80 percent the Sun’s mass and located 53 light-years away in the southern constellation Reticulum. The confirmed planet, HD 21749b, is about three times Earth’s size and 23 times its mass, orbits every 36 days, and has a surface temperature around 300 degrees Fahrenheit (150 degrees Celsius). It is the longest-period transiting planet within 100 light-years of the solar system, and it has the coolest surface temperature of a transiting exoplanet around a star brighter than 10th magnitude, or about 25 times fainter than the limit of unaided human vision. What’s even more exciting are hints the system holds a second candidate planet about the size of Earth that orbits the star every eight days. If confirmed, it could be the smallest TESS planet to date. In its primary two-year mission, TESS will observe nearly the whole sky, providing a rich catalog of worlds around nearby stars. Their proximity to Earth will enable detailed characterization of the planets through follow-up observations from space- and ground-based telescopes. But in its month-long stare into each sector, TESS records many additional phenomena, including comets, asteroids, flare stars, eclipsing binaries, white dwarf stars and supernovae, resulting in an astronomical treasure trove. In the first TESS sector alone, observed between July 25 and Aug. 22, 2018, the mission caught dozens of short-lived, or transient, events, including images of six supernovae in distant galaxies that were later seen by ground-based telescopes. These early observations hold the key to understanding a class of supernovae that serve as an important yardstick for cosmological studies. Type Ia supernovae form through two channels. One involves the merger of two orbiting white dwarfs, compact remnants of stars like the Sun. The other occurs in systems where a white dwarf draws gas from a normal star, gradually gaining mass until it becomes unstable and explodes. Astronomers don’t know which scenario is more common, but TESS could detect modifications to the early light of the explosion caused by the presence of stellar companion.
  • TESS Discovers Its Tiniest World To Date
    2019.06.27
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered a world between the sizes of Mars and Earth orbiting a bright, cool, nearby star. The planet, called L 98-59b, marks the smallest found by TESS yet. Two other worlds orbit the same star. While all three planets’ sizes are known, further study with other telescopes will be needed to determine if they have atmospheres and, if so, which gases are present. The L 98-59 worlds nearly double the number of small exoplanets — that is, planets beyond our solar system — that have the best potential for this kind of follow-up. L 98-59b is around 80% Earth’s size and about 10% smaller than the previous record holder discovered by TESS. Its host star, L 98-59, is an M dwarf about one-third the mass of the Sun and lies about 35 light-years away in the southern constellation Volans. While L 98-59b is a record for TESS, even smaller planets have been discovered in data collected by NASA’s Kepler satellite, including Kepler-37b, which is only 20% larger than the Moon. The two other worlds in the system, L 98-59c and L 98-59d, are respectively around 1.4 and 1.6 times Earth’s size. All three were discovered by TESS using transits, periodic dips in the star’s brightness caused when each planet passes in front of it.
  • Animations of TESS's First Exoplanets
    2019.09.02
    Illustration of the exoplanet LHS 3844 b. It is a rocky planet about 1.3 times Earth’s size located about 49 light-years away in the constellation Indus, making it among the closest transiting exoplanets known. The star is a cool M-type dwarf star about one-fifth the size of our Sun. Completing an orbit every 11 hours, the planet lies so close to its star that some of its rocky surface on the daytime side may form pools of molten lava.

    Credit: NASA/MIT/TESS

  • Exoplanet HD 21749 c Animation
    2019.08.07
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size world, named HD 21749 c. It’s about 89% of Earth’s size and orbits HD 21749, a K-type star with about 70% of the Sun’s mass located 53 light-years away in the southern constellation Reticulum, and is the second planet TESS has identified in the system. The new world is likely rocky and circles very close to its star, completing one orbit in just under eight days. The planet’s surface is likely very hot, with temperatures perhaps as high as 800 F (427 C). HD 21749 c's host star is bright and relatively nearby, and is therefore well suited to more detailed follow-up studies, which could provide critical information about the planet’s properties.

Live Events

  • NASA’s Newest Planet Hunter To Reveal New Results From Its First Year In Orbit Live Shots
    2019.07.25
    NASA’s Planet Hunter Reveals Exciting Discoveries in the Search for Strange New Worlds Look Up! Planets Orbit All The Stars You Can See In The Night Sky
    In its first year in orbit, NASA’s Transiting Exoplanet Survey Satellite, or TESS, scanned the skies in the southern hemisphere, where it discovered a variety of strange worlds. Next week, TESS will be unveiling some of its newest and most exciting discoveries about the planets orbiting the stars closest to us. It wasn’t that long ago that scientists weren’t sure if there were planets orbiting other stars, just as Earth orbits the Sun. With help from telescopes both in space and on the ground, we now know that our galaxy is teeming with exoplanets, or planets that lie beyond our solar system. In fact, when you look up at the night sky, consider that just about every star you see might have at least one planet orbiting it...maybe many more. NASA is diving deeper into the search for planets orbiting nearby stars with TESS and now as it enters year two, it will turn its gaze to the northern hemisphere, hunting for planets that orbit some of the stars we see each night with the naked eye.
  • NASA Preparing to Launch New Planet-Hunting Mission Live Shots
    2018.04.10
    NASA Preparing to Launch New Planet Hunting Mission Next Week
    Mission Expected to Discover Thousands of New Worlds Orbiting Nearby Stars
    NASA Scientists Available to Speak On the Hunt For New Worlds
    The hunt is on to discover new and exciting worlds! NASA’s Transiting Exoplanet Survey Satellite – TESS – is scheduled to launch April 16 to find thousands of planets orbiting stars outside our solar system, known as exoplanets. In the past ten years, NASA has discovered and studied thousands of these planets – including the TRAPPIST-1 system, which could have the ingredients to support life. TESS is expected to add thousands more planets to this growing list during its two-year mission, looking at the nearest and brightest stars in our galaxy to see if there are worlds hiding in their light.

    From molten lava and frigid icy planets, to bizarre places that rain rubies and sapphires and water-covered worlds, the possibilities of new worlds for the planet-hunter to find are limitless. Are Earth and the other planets in our solar system unique? Join NASA scientists from 6:00 a.m. to 12:00 p.m. EDT on Tuesday, April 10 – days before the launch – as they share some of the exciting discoveries they hope to find with the TESS mission.

    TESS will find promising planets that other NASA telescopes – like the Hubble Space Telescope and future James Webb Space Telescope – could look at in more detail to determine what their atmospheres are made of, and whether these unknown worlds could potentially support life. Suggested Questions:
    1. What is an exoplanet and why are scientists excited about them?
    2. How will this new mission help NASA in the search for life?
    3. Will this planet-hunter change the way we look at the stars in the night sky?
    4. Previous telescopes have found really unusual worlds. What kinds of planets are you looking forward to TESS discovering?
    5. Where can we learn more?
    Questions for longer interviews:
    1. Where will TESS orbit?
    2. What has been the biggest surprise in searching for exoplanets?
    3. How will TESS detect planets?
    4. What makes TESS different than other planet hunter missions?
    5. What does it look like when a planet crosses in front of the parent star?
    Live Shot Details: Location: NASA’s Goddard Space Flight Center/Greenbelt, Maryland

    Scientists:
    Dr. Paul Hertz / NASA Director of Astrophysics
    —or—
    Dr. Joshua Schlieder / NASA Scientist
    —or—
    Dr. Jennifer Burt / MIT Torres postdoctoral fellow
    —or—
    Natalia Guerrero / MIT Kavli TESS Objects of Interest Deputy Manager [ en Español ]z

  • Exoplanet Live Shots 2.23.17
    2017.02.21
    NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water. You can find graphics HERE that go with this story. The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water–key to life as we know it–under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.
  • Mercury Transit Live Shots May 9, 2016
    2016.05.02

    NASA will broadcast a stunning view of Mercury on May 9 as it journeys across the sun. The event, known as a transit, occurs when Mercury passes directly between Earth and the sun. This rare phenomenon will cause Mercury to look like a black dot gliding across the sun’s face. Mercury’s last transit was in 2006, and it won’t happen again until 2019!

    Starting at 7:12 a.m. EDT, Mercury will spend more than seven hours travelling across the sun. NASA’s Solar Dynamics Observatory will take the first near real time, ultra-high definition images ever for this event. This is also an opportunity for NASA scientists to fine tune the spacecraft’s cameras, using a method that can only be done during a transit.

  • 2017 Spring Equinox Live Shots
    2017.03.15
    March 20 Equinox Marks the Start of Spring in the Northern Hemisphere

    Dance of the Solar System is the First Solar Event of 2017

    Stay Tuned for the Big Event of 2017, the August Solar Eclipse!

    It may not feel like it this week in parts of the country, but spring begins in just a few days. March 20 kicks off the first day of astronomical spring in the Northern Hemisphere. On March 20, the day of the spring Equinox, the sun will pass directly over the Earth’s equator, giving the entire planet equal hours of day and night. This is the seasonal marker in Earth’s orbit around the sun when daylight hours begin to get longer than night.

    This dance of the solar system is just one celestial event we’ll see this year. On August 21 all 50 states in the U.S. will be in prime position to see a partial or even a total solar eclipse, which happens when the moon is in perfect position to blot out the sun’s bright disk. The last time the U.S. saw a coast-to-coast solar eclipse was in 1918! The path of totality runs from Oregon to South Carolina.

    NASA will lead an unprecedented science initiative during the eclipse that will draw on the collaboration of the public to help collect images, data and even temperature readings from across the nation during the hour-and-a-half it takes to cross the continent.

  • NASM 2016: The Search For Life
    2017.02.11
    On September 21, 2016, NASA scientists and stakeholders came together at the Smithsonian National Air and Space Museum for a presentation on the agency’s search for life beyond Earth. “The Search for Life” featured presentations from some of NASA’s leading scientists, including the late former astronaut, Dr. Piers Sellers. Through compelling visualizations, “The Search for Life” takes you on a journey through the solar system and beyond, exploring the possibility of life existing on Mars, the solar system’s outer moons, and exoplanets.

Related Items

  • Alien Atmospheres
    2013.12.03
    Since the early 1990's, astronomers have known that extrasolar planets, or "exoplanets," orbit stars light-years beyond our own solar system. Although most exoplanets are too distant to be directly imaged, detailed studies have been made of their size, composition, and even atmospheric makeup - but how? By observing periodic variations in the parent star's brightness and color, astronomers can indirectly determine an exoplanet's distance from its star, its size, and its mass. But to truly understand an exoplanet astronomers must study its atmosphere, and they do so by splitting apart the parent star's light during a planetary transit.
  • Looking for the Shadows of New Worlds
    2015.10.30
    Astronomers have used many different methods to discover planets beyond the solar system, but the most successful by far is transit photometry, which measures changes in a star's brightness caused by a mini-eclipse. When a planet crosses in front of its star along our line of sight, it blocks some of the star's light. If the dimming lasts for a set amount of time and occurs at regular intervals, it likely means an exoplanet is passing in front of, or transiting, the star once every orbital period. NASA’s Kepler Space Telescope has used this technique to become the most successful planet-hunting spacecraft to date, with more than a thousand established discoveries and many more awaiting confirmation. Missions carrying improved technology are now planned, but how much more can they tell us about alien planetary systems similar to our own? A great deal, according to recently published studies by Michael Hippke at the Institute for Data Analysis in Neukirchen-Vluyn, Germany, and Daniel Angerhausen, a postdoctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland. They show that in the best-case scenarios upcoming missions could uncover planetary moons, ringed worlds similar to Saturn, and even large collections of asteroids.
  • Join the Search for New Nearby Worlds
    2017.02.15
    A new website funded by NASA lets the public search for new worlds in the outer reaches of our solar system and in neighboring interstellar space. The website, called Backyard Worlds: Planet 9, allows everyone to participate in the search though brief movies made from images captured by NASA's Wide-field Infrared Survey Explorer (WISE) mission. The movies highlight sources that have gradually moved across the sky. The new website uses WISE all-sky data to search for unknown objects in and beyond our own solar system. In 2016, astronomers at the California Institute of Technology showed that several distant solar system objects possessed orbital features indicating they were affected by the gravity of an as-yet-undetected planet, which the researchers nicknamed "Planet Nine." If Planet Nine exists and is as bright as some predictions, it could show up in WISE data. The search also may discover more distant objects like brown dwarfs, sometimes called failed stars, in nearby interstellar space. These strange objects form like stars but evolve like planets, the coldest ones being much like Jupiter. On the website, people around the world can work their way through millions of "flipbooks," which are brief animations showing how small patches of the sky changed over several years. Moving objects flagged by users will be prioritized by the science team for later follow-up observations by professional astronomers. Participants will share credit for their discoveries in any scientific publications that result from the project.
  • Mercury Transit May 9, 2016
    2016.04.25
    This animation shows the May 9, 2016 transit of Mercury across the face of the Sun.