Lunar Reconnaissance Orbiter

The Lunar Reconnaissance Orbiter, or LRO, is a multipurpose NASA spacecraft launched in 2009 to make a comprehensive atlas of the Moon’s features and resources. Since launch, LRO has measured the coldest temperatures in the solar system inside the Moon’s permanently shadowed craters, detected evidence of water ice at the Moon’s south pole, seen hints of recent geologic activity on the Moon, found newly-formed craters from present-day meteorite impacts, tested spaceborne laser communication technology, and much more.

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Video Features

  • Tour of the Moon 4K Redux
    2018.04.09
    In the fall of 2011, the Lunar Reconnaissance Orbiter (LRO) mission released its original Tour of the Moon, a five-minute animation that takes the viewer on a virtual tour of our nearest neighbor in space. Six years later, the tour has been recreated in eye-popping 4K resolution, using the same camera path and drawing from the vastly expanded data trove collected by LRO in the intervening years. The tour visits a number of interesting sites chosen to illustrate a variety of lunar terrain features. Some are on the near side and are familiar to both professional and amateur observers on Earth, while others can only be seen clearly from space. Some are large and old (Orientale, South Pole-Aitken), others are smaller and younger (Tycho, Aristarchus). Constantly shadowed areas near the poles are hard to photograph but easier to measure with altimetry, while several of the Apollo landing sites, all relatively near the equator, have been imaged at resolutions as high as 25 centimeters (10 inches) per pixel. The new tour highlights the mineral composition of the Aristarchus plateau, evidence for surface water ice in certain spots near the south pole, and the mapping of gravity in and around the Orientale basin.
  • Moonlight (Clair de Lune)
    2018.07.20
    This visualization attempts to capture the mood of Claude Debussy's best-known composition, Clair de Lune (moonlight in French). The piece was published in 1905 as the third of four movements in the composer's Suite Bergamasque, and unlike the other parts of this work, Clair is quiet, contemplative, and slightly melancholy, evoking the feeling of a solitary walk through a moonlit garden. The visuals were composed like a nature documentary, with clean cuts and a mostly stationary virtual camera. The viewer follows the Sun throughout a lunar day, seeing sunrises and then sunsets over prominent features on the Moon. The sprawling ray system surrounding Copernicus crater, for example, is revealed beneath receding shadows at sunrise and later slips back into darkness as night encroaches. The visualization was created to accompany a performance of Clair de Lune by the National Symphony Orchestra Pops, led by conductor Emil de Cou, at the Kennedy Center for the Performing Arts in Washington, DC, on June 1 and 2, 2018, as part of a celebration of NASA's 60th anniversary. The visualization uses a digital 3D model of the Moon built from Lunar Reconnaissance Orbiter global elevation maps and image mosaics. The lighting is derived from actual Sun angles during lunar days in 2018.
  • Moon Phase and Libration, 2018
    2017.12.18

    Dial-A-Moon

    Month: Day: UT Hour:



    Click on the image to download a high-resolution version with labels for craters near the terminator.

    The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2018, at hourly intervals. Until the end of 2018, the initial Dial-A-Moon image will be the frame from this animation for the current hour.


    More in this series:
    Moon Phase and Libration Gallery


    Lunar Reconnaissance Orbiter (LRO) has been in orbit around the Moon since the summer of 2009. Its laser altimeter (LOLA) and camera (LROC) are recording the rugged, airless lunar terrain in exceptional detail, making it possible to visualize the Moon with unprecedented fidelity. This is especially evident in the long shadows cast near the terminator, or day-night line. The pummeled, craggy landscape thrown into high relief at the terminator would be impossible to recreate in the computer without global terrain maps like those from LRO.

    The Moon always keeps the same face to us, but not exactly the same face. Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it's wobbling. This wobble is called libration.

    The word comes from the Latin for "balance scale" (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides. The sub-Earth point gives the amount of libration in longitude and latitude. The sub-Earth point is also the apparent center of the Moon's disk and the location on the Moon where the Earth is directly overhead.

    The Moon is subject to other motions as well. It appears to roll back and forth around the sub-Earth point. The roll angle is given by the position angle of the axis, which is the angle of the Moon's north pole relative to celestial north. The Moon also approaches and recedes from us, appearing to grow and shrink. The two extremes, called perigee (near) and apogee (far), differ by about 14%.

    The most noticed monthly variation in the Moon's appearance is the cycle of phases, caused by the changing angle of the Sun as the Moon orbits the Earth. The cycle begins with the waxing (growing) crescent Moon visible in the west just after sunset. By first quarter, the Moon is high in the sky at sunset and sets around midnight. The full Moon rises at sunset and is high in the sky at midnight. The third quarter Moon is often surprisingly conspicuous in the daylit western sky long after sunrise.

    Celestial north is up in these images, corresponding to the view from the northern hemisphere. The descriptions of the print resolution stills also assume a northern hemisphere orientation. (There is also a south-up version of this page.)

    The Moon's Orbit

    From this birdseye view, it's somewhat easier to see that the phases of the Moon are an effect of the changing angles of the sun, Moon and Earth. The Moon is full when its orbit places it in the middle of the night side of the Earth. First and Third Quarter Moon occur when the Moon is along the day-night line on the Earth.

    The First Point of Aries is at the 3 o'clock position in the image. The sun is in this direction at the March equinox. You can check this by freezing the animation at the 1:03 mark, or by freezing the full animation with the time stamp near March 20 at 10:00 UTC. This direction serves as the zero point for both ecliptic longitude and right ascension.

    The north pole of the Earth is tilted 23.5 degrees toward the 12 o'clock position at the top of the image. The tilt of the Earth is important for understanding why the north pole of the Moon seems to swing back and forth. In the full animation, watch both the orbit and the "gyroscope" Moon in the lower left. The widest swings happen when the Moon is at the 3 o'clock and 9 o'clock positions. When the Moon is at the 3 o'clock position, the ground we're standing on is tilted to the left when we look at the Moon. At the 9 o'clock position, it's tilted to the right. The tilt itself doesn't change. We're just turned around, looking in the opposite direction.

    The subsolar and sub-Earth points are the locations on the Moon's surface where the sun or the Earth are directly overhead, at the zenith. A line pointing straight up at one of these points will be pointing toward the sun or the Earth. The sub-Earth point is also the apparent center of the Moon's disk as observed from the Earth.

    In the animation, the blue dot is the sub-Earth point, and the yellow dot is the subsolar point. The lunar latitude and longitude of the sub-Earth point is a measure of the Moon's libration. For example, when the blue dot moves to the left of the meridian (the line at 0 degrees longitude), an extra bit of the Moon's western limb is rotating into view, and when it moves above the equator, a bit of the far side beyond the north pole becomes visible.

    At any given time, half of the Moon is in sunlight, and the subsolar point is in the center of the lit half. Full Moon occurs when the subsolar point is near the center of the Moon's disk. When the subsolar point is somewhere on the far side of the Moon, observers on Earth see a crescent phase.

    The Moon's orbit around the Earth isn't a perfect circle. The orbit is slightly elliptical, and because of that, the Moon's distance from the Earth varies between 28 and 32 Earth diameters, or about 356,400 and 406,700 kilometers. In each orbit, the smallest distance is called perigee, from Greek words meaning "near earth," while the greatest distance is called apogee. The Moon looks largest at perigee because that's when it's closest to us.

    The animation follows the imaginary line connecting the Earth and the Moon as it sweeps around the Moon's orbit. From this vantage point, it's easy to see the variation in the Moon's distance. Both the distance and the sizes of the Earth and Moon are to scale in this view. In the HD-resolution frames, the Earth is 50 pixels wide, the Moon is 14 pixels wide, and the distance between them is about 1500 pixels, on average.

    Note too that the Earth appears to go through phases just like the Moon does. For someone standing on the surface of the Moon, the sun and the stars rise and set, but the Earth doesn't move in the sky. It goes through a monthly sequence of phases as the sun angle changes. The phases are the opposite of the Moon's. During New Moon here, the Earth is full as viewed from the Moon.

  • Moon Phase and Libration, 2018 South Up
    2017.12.18

    Dial-A-Moon

    Month: Day: UT Hour:



    Click on the image to download a high-resolution version with labels for craters near the terminator.

    The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2018, at hourly intervals. Until the end of 2018, the initial Dial-A-Moon image will be the frame from this animation for the current hour.


    More in this series:
    Moon Phase and Libration Gallery


    Lunar Reconnaissance Orbiter (LRO) has been in orbit around the Moon since the summer of 2009. Its laser altimeter (LOLA) and camera (LROC) are recording the rugged, airless lunar terrain in exceptional detail, making it possible to visualize the Moon with unprecedented fidelity. This is especially evident in the long shadows cast near the terminator, or day-night line. The pummeled, craggy landscape thrown into high relief at the terminator would be impossible to recreate in the computer without global terrain maps like those from LRO.

    The Moon always keeps the same face to us, but not exactly the same face. Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it's wobbling. This wobble is called libration.

    The word comes from the Latin for "balance scale" (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides. The sub-Earth point gives the amount of libration in longitude and latitude. The sub-Earth point is also the apparent center of the Moon's disk and the location on the Moon where the Earth is directly overhead.

    The Moon is subject to other motions as well. It appears to roll back and forth around the sub-Earth point. The roll angle is given by the position angle of the axis, which is the angle of the Moon's north pole relative to celestial north. The Moon also approaches and recedes from us, appearing to grow and shrink. The two extremes, called perigee (near) and apogee (far), differ by more than 10%.

    The most noticed monthly variation in the Moon's appearance is the cycle of phases, caused by the changing angle of the Sun as the Moon orbits the Earth. The cycle begins with the waxing (growing) crescent Moon visible in the west just after sunset. By first quarter, the Moon is high in the sky at sunset and sets around midnight. The full Moon rises at sunset and is high in the sky at midnight. The third quarter Moon is often surprisingly conspicuous in the daylit western sky long after sunrise.

    Celestial south is up in these images, corresponding to the view from the southern hemisphere. The descriptions of the print resolution stills also assume a southern hemisphere orientation. (There is also a north-up version of this page.)

    The Moon's Orbit

    From this birdseye view, it's somewhat easier to see that the phases of the Moon are an effect of the changing angles of the sun, Moon and Earth. The Moon is full when its orbit places it in the middle of the night side of the Earth. First and Third Quarter Moon occur when the Moon is along the day-night line on the Earth.

    The First Point of Aries is at the 3 o'clock position in the image. The sun is in this direction at the March equinox. You can check this by freezing the animation at the 1:03 mark, or by freezing the full animation with the time stamp near March 20 at 10:00 UTC. This direction serves as the zero point for both ecliptic longitude and right ascension.

    The south pole of the Earth is tilted 23.5 degrees toward the 12 o'clock position at the top of the image. The tilt of the Earth is important for understanding why the north pole of the Moon seems to swing back and forth. In the full animation, watch both the orbit and the "gyroscope" Moon in the lower left. The widest swings happen when the Moon is at the 3 o'clock and 9 o'clock positions. When the Moon is at the 3 o'clock position, the ground we're standing on is tilted to the left when we look at the Moon. At the 9 o'clock position, it's tilted to the right. The tilt itself doesn't change. We're just turned around, looking in the opposite direction.

    The subsolar and sub-Earth points are the locations on the Moon's surface where the sun or the Earth are directly overhead, at the zenith. A line pointing straight up at one of these points will be pointing toward the sun or the Earth. The sub-Earth point is also the apparent center of the Moon's disk as observed from the Earth.

    In the animation, the blue dot is the sub-Earth point, and the yellow dot is the subsolar point. The lunar latitude and longitude of the sub-Earth point is a measure of the Moon's libration. For example, when the blue dot moves to the left of the meridian (the line at 0 degrees longitude), an extra bit of the Moon's eastern limb is rotating into view, and when it moves above the equator, a bit of the far side beyond the south pole becomes visible.

    At any given time, half of the Moon is in sunlight, and the subsolar point is in the center of the lit half. Full Moon occurs when the subsolar point is near the center of the Moon's disk. When the subsolar point is somewhere on the far side of the Moon, observers on Earth see a crescent phase.

    The Moon's orbit around the Earth isn't a perfect circle. The orbit is slightly elliptical, and because of that, the Moon's distance from the Earth varies between 28 and 32 Earth diameters, or about 356,400 and 406,700 kilometers. In each orbit, the smallest distance is called perigee, from Greek words meaning "near earth," while the greatest distance is called apogee. The Moon looks largest at perigee because that's when it's closest to us.

    The animation follows the imaginary line connecting the Earth and the Moon as it sweeps around the Moon's orbit. From this vantage point, it's easy to see the variation in the Moon's distance. Both the distance and the sizes of the Earth and Moon are to scale in this view. In the HD-resolution frames, the Earth is 50 pixels wide, the Moon is 14 pixels wide, and the distance between them is about 1500 pixels, on average.

    Note too that the Earth appears to go through phases just like the Moon does. For someone standing on the surface of the Moon, the sun and the stars rise and set, but the Earth doesn't move in the sky. It goes through a monthly sequence of phases as the sun angle changes. The phases are the opposite of the Moon's. During New Moon here, the Earth is full as viewed from the Moon.

  • NASA at Fenway
    2018.07.03
    On May 30th, 2018 NASA descended upon the historic Fenway Park, home of the Boston Red Sox Major League Baseball team, to participate in a STEM Day public engagement event. This collaborative effort was led by members of the Solar System Exploration Division at NASA’s Goddard Space Flight Center with the following participants: • Lunar Reconnaissance Orbiter (LRO), GSFC • Astromaterials Research & Exploration Science (ARES), JSC • Orion, JSC • Chandra X-Ray Center, Smithsonian Astrophysical Observatory (SAO) • NASA Space Science Education Consortium/Heliophysics, SAO • CRaTER Instrument, University of New Hampshire • RIS4E, Stonybrook University

    Over 4000 students and teachers from across New England made the trip to see exhibits from the 7 different NASA missions and projects, demonstrations of space science concepts, and presentations from NASA scientists. Noah Petro, the Project Scientist from the Lunar Reconnaissance Orbiter Mission, led this endeavor, and astronaut Sunita Williams was the featured guest speaker. The list of speakers also included Elizabeth Rampe (JSC), Daniel Castro (Chandra X-ray Observatory), Kelly Korreck (SAO), David Draper (JSC), and Kimberly Kowal Arcand (Chandra X-ray Observatory). Molly Wasser (ADNET/GSFC) served as the Event Lead.

    After the STEM event, NASA Goddard scientist and professional harpist, Maria Banks, played the National Anthem before the Red Sox game. It was a fun day of science and sports.

  • 100 Lunar Days - Parts I and II
    2017.10.06
    In October of 2017, Lunar Reconnaissance Orbiter (LRO) celebrates one hundred days of collecting scientific data at the Moon. One hundred Moon days. That's 100 opportunities to observe changes from night to day, photograph the surface at different Sun angles, measure rising and falling temperatures, and study the way certain chemicals react to the daily light and temperature cycle, among other things. But you might be wondering...

    What is a lunar day?

    What do we mean when we say that LRO has been at the Moon for 100 lunar days? The short answer is this: A day is the length of time between two noons or sunsets. That's 24 hours on Earth, 708.7 hours (29.53 Earth days) on the Moon. We can see a day passing on the Moon by watching its month-long cycle of phases, and as of October 16, 2017, LRO has watched this cycle 100 times since the start of its exploration and science mission on September 15, 2009. But as often happens in astronomy, the situation's actually a little more complicated. The trouble starts with merely nailing down a definition of the word day. At any given location on the Earth, a local solar day is the time it takes the Sun to return to the same point in the sky. To be more precise, we define a line in the sky, the meridian, which runs between due north and due south and passes through the zenith (the straight-up point). Local noon is the time when the Sun is centered on the meridian, and a local solar day is the time between two successive local noons. The length of this kind of day varies throughout the year. Currently, it can be as much as 21 seconds shorter or 29 seconds longer than 24 hours. This variation is due to the eccentricity of the Earth's orbit (the orbit is an ellipse, not a circle), and the obliquity of the ecliptic (the Earth's axis is tilted relative to its orbit). So that we don't have to reset our clocks all the time, it's convenient to define a mean solar day, the average of the local solar day over a full year. A mean solar day is exactly 24 hours long. In fact, we define an hour as 1/24 of a mean solar day. The mean solar day can't be the average over any arbitrary year. The eccentricity and obliquity vary over time, and because of precession of the equinoxes, the effect of obliquity slides through the calendar, alternately reinforcing and canceling the effect of eccentricity over tens of thousands of years. The Earth is also slowing down, primarily due to tidal interactions with the Moon. The mean solar day is the theoretical average local solar day, calculated by fixing the eccentricity, obliquity, precession, and rotation rate to the values at noon in Greenwich, England, on December 31, 1899, using the theory of the Sun's apparent motion developed by Simon Newcomb in the 1890's. We now have extremely accurate atomic clocks. We define the length of a second as a certain number of waves in the radiation from a cesium atom, and we say that a mean solar day is 86400 of these seconds. For historical continuity, the number of waves was chosen so that this second is 1/86400 of the mean solar day defined by Newcomb's theory. The concept of a solar day can be extended to other bodies in the solar system, including our Moon. A mean solar day on the Moon, a lunar day for short, is 29.5306 Earth days. Local lunar days can vary even more than solar days on Earth, over 6 hours shorter or 7 hours longer than the mean. The 100 lunar days celebrated by LRO in October of 2017 are mean lunar days. Because the Moon is tidally locked to the Earth, it always shows the Earth the same face. This also means that it rotates at the same rate that it orbits. A lunar day takes exactly as long as one complete orbit relative to the Sun. A lunar day also corresponds to one complete cycle of the phases visible from Earth, so a lunar day is the same as a synodic month. At this point, it shouldn't surprise you that there are other kinds of days (sidereal, for example) and months (anomalistic and draconic, to name two). But that's a story for another time.
  • Jack Schmitt: From Apollo 17 to LRO
    2017.11.20
    December 11, 2017 will mark the 45th anniversary of the day NASA's Apollo 17 mission landed on the Moon. This video connects that history to the current Lunar Reconnaissance Orbiter mission through the eyes of astronaut Harrison Jack Schmitt. As a geologist and Apollo 17 crewmember, Schmitt has a unique perspective about how data being collected by LRO enhances our current understanding of lunar science and lays the groundwork for future explorers.
  • Moon Phase and Libration, 2017
    2016.12.22
    The visualization shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2017, at hourly intervals.
  • Moon Phase and Libration, 2017 South Up
    2016.12.22
    The visualization shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2017, at hourly intervals.
  • Baseball Hits an Eclipse
    2017.09.21

    On Aug. 21, 2017, a total solar eclipse caused the Salem-Keizer Volcanoes Minor League Baseball game to experience the first ever "Eclipse Delay" in professional baseball history. This wasn't a chance occurrence, however, but a planned event. With the Sun and the Moon set to provide the spectacle in the sky, representatives from the Lunar Reconnaissance Orbiter mission at NASA's Goddard Space Flight Center joined forces with the Volcanoes' management team to coordinate an "EclipseFest" on the grounds of the stadium. Over the course of a four-day home series, NASA showcased science experiments, presentations, and videos inside the ballpark for all to see and learn from. Noah Petro, the deputy project scientist for LRO, led the endeavor, bringing more eyes to the field of lunar science.

    This video shows what took place at this "EclipseFest" in Keizer, Oregon, and how science and sports combined for one of the most unique viewing experiences in the country.

  • The Moon and More
    2016.10.03
    "The Moon and More" is a music video featuring musicians Javier Colon (Season 1 winner of NBC's "The Voice"), and Matt Cusson in collaboration with NASA's Goddard Space Flight Center and the Lunar Reconnaissance Orbiter (LRO) mission.
  • The Moon's Role in a Solar Eclipse
    2017.07.21
    While the sun is the main focus of a solar eclipse, our moon plays the most crucial role in creating this unique event. This video tutorial explains what happens during a total solar eclipse and a partial eclipse and how often they both occur. The video also explains how a solar eclipse differs from a lunar eclipse, and gives a helpful tip on how to remember the difference. In addition, the video examines how the two parts of the moon’s shadow, the umbra and penumbra, affect how we see an eclipse on the Earth, and illustrates the surprising true shape of the umbra. The video concludes by highlighting how data from NASA’s Lunar Reconnaissance Orbiter has helped us better map a solar eclipse’s path of totality. Visualizations included in this piece showcase the August 21, 2017 total solar eclipse happening in the United States.
  • Tracing the 2017 Solar Eclipse
    2016.12.14
    When depicting an eclipse path, data visualizers have usually chosen to represent the moon's shadow as an oval. By bringing in a variety of NASA data sets, visualizer Ernie Wright has created a new and more accurate representation of the eclipse. For the first time, we are able to see that the moon's shadow is better represented as a polygon. This more complicated shape is based NASA's Lunar Reconnaissance Orbiter's view of the mountains and valleys that form the moon's jagged edge. By combining moon's terrain, heights of land forms on Earth, and the angle of the sun, Wright is able to show the eclipse path with the greatest accuracy to date.
  • Rima Prinz and Vera
    2016.08.01
    Rima Prinz is a channel (a lunar sinuous rille) carved by lava flow. It lies just north of Prinz crater, about 100 km east of the Aristarchus Plateau in Oceanus Procellarum. The source of the lava is a volcanic depression named Vera. Together they create the appearance of a snake with its head near the rim of Prinz crater and its body stretching some 75 km, first to the west and then turning sharply north. Vera may have formed as a lava lake fed by multiple eruptions of a fire fountain volcano, similar to Mauna Ulu in Hawaii, but vastly larger. Rima Prinz is a hundred times deeper and ten times longer than similar channels on Earth. The visualization uses Lunar Reconnaissance Orbiter Camera (LROC) imagery at multiple resolutions to show both small details and global context. It also uses a combination of elevation datasets derived from both LROC narrow-angle camera images and laser altimetry (LOLA). More information about the LROC datasets can be found here. The narrated videos are available in both English and Spanish.
  • Lunar Swirls: Reiner Gamma
    2017.03.27
    Lunar swirls are bright, often sinuous features with the diffuse appearance of abstract airbrush paintings. They are unique to the Moon and have long defied easy explanation. Five papers recently published in Icarus (1, 2, 3), JGR: Space Physics (4), and JGR: Planets (5) use a combination of computer modeling and the data gathered by Lunar Reconnaissance Orbiter (LRO) and other recent lunar missions to shed new light on the origin of these unusual surface decorations. Reiner Gamma, a bright patch amid the otherwise dark Oceanus Procellarum mare, is perhaps the most spectacular example of a lunar swirl. Through backyard telescopes near full Moon, it looks like a small figure-8 on its side. LRO's view from orbit reveals tendrils and daughter swirls that extend for several hundred kilometers. The animation zooms up on an LRO wide-angle camera mosaic of Reiner Gamma, then tilts the view to show that this large swirl is entirely two-dimensional — it's not a mountain range or a valley, but instead looks painted onto the surface. The narrated videos are available in both English and Spanish.
  • Temperature, Reflectance Point to Frost near the Moon's Poles
    2017.05.31

    Scientists studying data from Lunar Reconnaissance Orbiter (LRO) have found evidence of surface frost near the poles on the Moon. Elizabeth Fisher, Paul Lucey, and their colleagues combined temperature data from LRO's Diviner instrument with reflectance from its laser altimeter (LOLA) to find places that are cold enough and shiny enough to indicate the possible presence of surface water ice. Their results appear in the August, 2017 issue of the journal Icarus.

  • Moon Phase and Libration, 2016
    2015.12.10
    The visualization shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2016, at hourly intervals.
  • Moon Phase and Libration, 2016 South Up
    2015.12.10
    The visualization shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2016, at hourly intervals.
  • Supermoon Lunar Eclipse
    2015.08.31
    On the night of September 27th, 2015, a supermoon lunar ecllipse will be viewable in the night sky for those living in North and South America. Those living in Europe and Africa can view it in the early morning hours of September 28th. This video explains what a supermoon lunar eclipse is, and how rare it has been over the last century.
  • Moon Phase and Libration, from the Other Side
    2015.02.04
    A number of people who've seen the annual lunar phase and libration videos have asked what the other side of the Moon looks like, the side that can't be seen from the Earth. This video answers that question. (Update: The video was selected for the SIGGRAPH 2015 Computer Animation Festival.) Just like the near side, the far side goes through a complete cycle of phases. But the terrain of the far side is quite different. It lacks the large dark spots, called maria, that make up the familiar Man in the Moon on the near side. Instead, craters of all sizes crowd together over the entire far side. The far side is also home to one of the largest and oldest impact features in the solar system, the South Pole-Aitken basin, visible here as a slightly darker bruise covering the bottom third of the disk. The far side was first seen in a handful of grainy images returned by the Soviet Luna 3 probe, which swung around the Moon in October, 1959. Lunar Reconnaissance Orbiter was launched fifty years later, and since then it has returned hundreds of terabytes of data, allowing LRO scientists to create extremely detailed and accurate maps of the far side. Those maps were used to create the imagery seen here. In the first of the two viewpoints, the virtual camera is positioned along the Earth-Moon line at a distance of 30 Earth diameters from the Moon and 60 ED from the Earth. The focal length is equivalent to a 2000 mm telephoto lens on a 35 mm SLR, making the horizontal field of view about one degree. The view is consistent with what you might see through an amateur telescope at these distances. In the second view, the virtual camera is much closer to the Moon, only 1.2 ED, versus 31 ED from Earth. The camera focal length has been reduced to 80 mm, giving a 25° horizontal field. The result is an Earth that appears much smaller, more closely resembling the way it would look to the eye from the surface of the Moon.
  • Driving A Lunar Spacecraft
    2015.07.27
    This video explains how NASA operates the Lunar Reconnaissance Orbiter spacecraft around the Moon.

    For complete transcript, click here.

    Watch this video on the NASAexplorer YouTube channel.

  • New Craters on the Moon
    2015.03.17
    Planetary scientists believe that small impacts regularly bombard the Moon, but until recently, they’ve had no way to distinguish new craters from the already pockmarked lunar surface. In 2009, NASA’s Lunar Reconnaissance Orbiter (LRO) arrived at the Moon and began taking high-resolution photographs. By comparing pictures taken early in the mission with more recent images, the LRO camera team has discovered more than two-dozen new impact craters – including an 18-meter-wide crater caused by a bright flash on March 17, 2013. Learn more about this finding.
  • Supermoon 2014
    2014.08.08
    On August 10, 2014, the Moon will be full at the same time that it is closest to Earth for the year. This coincidence is sometimes called a supermoon. The Moon's orbit is very slightly elliptical and therefore somewhat off-center relative to the Earth. Each month, the Moon passes through points in its orbit called perigee and apogee, the closest and farthest points from the Earth for that month. Some perigees are a little closer than others. The closest perigee for 2014 occurs on August 10 at around 17:49 Universal Time, when the Moon will be 356,896 kilometers (221,765 miles) away. As it happens, this is only a few minutes before the time of peak full Moon at 18:10 UT, when the Moon's ecliptic longitude differs from the Sun's by exactly 180 degrees. How often does this happen? The period between perigees, called the anomalistic month, is 27.55 days, on average, while the time between Full Moons, called the synodic month, is 29.53 days. These two periods sync up every 413 days, or 1.13 years. 15 anomalistic months are about as long as 14 synodic months, so that's how often the pattern repeats. Recently, a much broader definition of "supermoon" has taken hold. It includes both Full and New Moons, and perigee merely needs to be "close enough," generally within a couple of days. By this definition, there are six or seven supermoons every year, half of which can't be observed. Not so super! The actual shape of the Moon's orbit is another source of confusion. The orbit is often depicted as an almost cigar-shaped ellipse, but this is a misleading exaggeration. If you were to draw the orbit on a sheet of paper, its deviation from a perfect circle would be less than the thickness of your pencil point. The 50,000 kilometer (30,000 mile) difference between perigee and apogee is almost entirely due to the orbit being off-center. The difference between the semimajor and semiminor axes is less than 1000 kilometers (600 miles). The animation begins in mid-July, showing that perigee and Full Moon miss each other by about a day. It then shows apogee on July 28, when the Moon is almost 32 Earth diameters away. It ends on August 10, the day of the supermoon, when the distance to the Moon is 28 Earth diameters. The Moon graphic in the upper left shows the change in the Moon's apparent size as it moves closer and farther in its orbit. (The relative sizes of the Earth and Moon in the main orbit graphic are exaggerated by a factor of 15 to make them more easily visible.)
  • A New Look at the Apollo 11 Landing Site
    2014.07.18
    Apollo 11 landed on the Moon on July 20th, 1969, a little after 4:00 in the afternoon Eastern Daylight Time. The Lunar Module, nicknamed Eagle and flown by Neil Armstrong and Edwin "Buzz" Aldrin, touched down near the southern rim of the Sea of Tranquility, one of the large, dark basins that contribute to the Man in the Moon visible from Earth. Armstrong and Aldrin spent about two hours outside the LM setting up experiments and collecting samples. At one point, Armstrong ventured east of the LM to examine a small crater, dubbed Little West, that he'd flown over just before landing. The trails of disturbed regolith created by the astronauts' boots are still clearly visible in photographs of the landing site taken by the Lunar Reconnaissance Orbiter (LRO) narrow-angle camera (LROC) more than four decades later. LROC imagery makes it possible to visit the landing site in a whole new way by flying around a three-dimensional model of the site. LROC scientists created the digital elevation model using a stereo pair of images. Each image in the pair shows the site from a slightly different angle, allowing sophisticated software to infer the shape of the terrain, similar to the way that left and right eye views are combined in the brain to produce the perception of depth. The animator draped an LROC photograph over the terrain model. He also added a 3D model of the LM descent stage—the real LM in the photograph looks oddly flat when viewed at an oblique angle. Although the area around the site is relatively flat by lunar standards, West Crater (the big brother of the crater visited by Armstrong) appears in dramatic relief near the eastern edge of the terrain model. Ejecta from West comprises the boulders that Armstrong had to avoid as he searched for a safe landing site. Apollo 11 was the first of six increasingly ambitious crewed lunar landings. The exploration of the lunar surface by the Apollo astronauts, when combined with the wealth of remote sensing data now being returned by LRO, continues to inform our understanding of our nearest neighbor in space.
  • Evolution of the Moon
    2012.03.14
    From year to year, the moon never seems to change. Craters and other formations appear to be permanent now, but the moon didn't always look like this. Thanks to NASA's Lunar Reconnaissance Orbiter, we now have a better look at some of the moon's history. Learn more in this video!

    This entry contains the Evolution of the Moon video in mutliple formats, including stereoscopic 3D in both side-by-side and individual left/right channel versions. It also includes a narrated and non-narrated version. Each individual video is labeled to make it easier to find the version that works for you!

  • The Moon As Art Contest
    2014.06.18
    To celebrate its 5th Anniversary, the Lunar Reconnaissance Orbiter mission decided to hold a contest to pick a cover image for "The Moon As Art" collection. This collection features a variety of beautiful visuals that were created using data gathered by LRO over the first 4.5 years of operations. 5 images were selected by the LRO team to put up for a public vote. Did your favorite image win? Watch this video to find out!
  • Need To Know: Lunar Eclipse and LRO
    2014.04.08
    On April 15th, 2014 there will be a total lunar eclipse visible from North America. Noah Petro, LRO Deputy Project Scientist, discusses this unique event and what effect it will have on the Lunar Reconnaissance Orbiter (LRO).
  • Jim Garvin's Top "Pics" - LROC Images
    2014.03.24
    In this video series, NASA Scientist Jim Garvin highlights his favorite pictures taken throughout the solar system. This episode focuses on images taken by LROC – the Lunar Reconnaissance Orbiter Camera. Jim explains which pictures made his “top 5” list.
  • Earthrise: The 45th Anniversary
    2013.12.20
    In December of 1968, the crew of Apollo 8 became the first people to leave our home planet and travel to another body in space. But as crew members Frank Borman, James Lovell, and William Anders all later recalled, the most important thing they discovered was Earth. Using photo mosaics and elevation data from Lunar Reconnaissance Orbiter (LRO), this video commemorates the 45th anniversary of Apollo 8's historic flight by recreating the moment when the crew first saw and photographed the Earth rising from behind the Moon. Narrator Andrew Chaikin, author of A Man on the Moon, sets the scene for a three-minute visualization of the view from both inside and outside the spacecraft accompanied by the onboard audio of the astronauts. The visualization draws on numerous historical sources, including the actual cloud pattern on Earth from the ESSA-7 satellite and dozens of photographs taken by Apollo 8, and it reveals new, historically significant information about the Earthrise photographs. It has not been widely known, for example, that the spacecraft was rolling when the photos were taken, and that it was this roll that brought the Earth into view. The visualization establishes the precise timing of the roll and, for the first time ever, identifies which window each photograph was taken from. The key to the new work is a set of vertical stereo photographs taken by a camera mounted in the Command Module's rendezvous window and pointing straight down onto the lunar surface. It automatically photographed the surface every 20 seconds. By registering each photograph to a model of the terrain based on LRO data, the orientation of the spacecraft can be precisely determined. A Google Hangout discussion of this visualization between Ernie Wright (creator of the visualization), Andrew Chaikin (narrator and script writer for the visualization and author of A Man on the Moon), John Keller (LRO project scientist), and Aries Keck (NASA media specialist) was held on December 20, 2013. A replay of that hangout is available here. Ernie Wright presented a talk about the making of this animation at the 2014 SIGGRAPH Conference in Vancouver. He also wrote a NASA Wavelength blog entry about Earthrise that includes links to educator resources related to LRO.
  • A Narrated Tour of the Moon
    2012.03.14
    Although the moon has remained largely unchanged during human history, our understanding of it and how it has evolved over time has evolved dramatically. Thanks to new measurements, we have new and unprecedented views of its surface, along with new insight into how it and other rocky planets in our solar system came to look the way they do. See some of the sights and learn more about the moon here!
  • Peeking Into Lunar Pits
    2014.07.17
    Since 2009, NASA’s Lunar Reconnaissance Orbiter (LRO) has spotted hundreds of conspicuous holes on the Moon. These steep-walled “pits" vary from a few meters to nearly 1 kilometer wide, and can reach depths of over 100 meters. Scientists think that pits may form when part of the Moon’s surface collapses above a lava tube, and high-resolution photographs from LRO suggest that many of the pits widen underground. If so, lunar pits might provide shelter from radiation, meteorite impacts, and extreme temperatures, making them valuable sites for future exploration.
  • Understanding Lunar Eclipses
    2014.04.08
    What can cause the full Moon to quickly darken, then glow red? A lunar eclipse: a striking display of orbital mechanics that occurs when the Moon passes through the Earth's shadow. To learn more, watch the video below.
  • Earthrise: The 45th Anniversary
    2013.12.20
    In December of 1968, the crew of Apollo 8 became the first people to leave our home planet and travel to another body in space. But as crew members Frank Borman, James Lovell, and William Anders all later recalled, the most important thing they discovered was Earth. Using photo mosaics and elevation data from Lunar Reconnaissance Orbiter (LRO), this video commemorates the 45th anniversary of Apollo 8's historic flight by recreating the moment when the crew first saw and photographed the Earth rising from behind the Moon. Narrator Andrew Chaikin, author of A Man on the Moon, sets the scene for a three-minute visualization of the view from both inside and outside the spacecraft accompanied by the onboard audio of the astronauts. The visualization draws on numerous historical sources, including the actual cloud pattern on Earth from the ESSA-7 satellite and dozens of photographs taken by Apollo 8, and it reveals new, historically significant information about the Earthrise photographs. It has not been widely known, for example, that the spacecraft was rolling when the photos were taken, and that it was this roll that brought the Earth into view. The visualization establishes the precise timing of the roll and, for the first time ever, identifies which window each photograph was taken from. The key to the new work is a set of vertical stereo photographs taken by a camera mounted in the Command Module's rendezvous window and pointing straight down onto the lunar surface. It automatically photographed the surface every 20 seconds. By registering each photograph to a model of the terrain based on LRO data, the orientation of the spacecraft can be precisely determined. A Google Hangout discussion of this visualization between Ernie Wright (creator of the visualization), Andrew Chaikin (narrator and script writer for the visualization and author of A Man on the Moon), John Keller (LRO project scientist), and Aries Keck (NASA media specialist) was held on December 20, 2013. A replay of that hangout is available here. This NASA Wavelength blog entry about Earthrise includes links to educator resources related to LRO.
  • LRO 4th Anniversary
    2013.06.18
    Four years ago, NASA made a long promised return visit to a place so legendary in the history of space exploration that it felt like a reunion with a long lost relative. With the liftoff of the Lunar Reconnaissance Orbiter (LRO), NASA made a bold statement about its commitment to exploring Earth's closest neighbor, as well as other parts of the solar system. In the years since it rose on its rocket, LRO has amassed a stunning array of data on a wide range of subjects. From vital research about the formation of the early solar system, to fundamental research about the structure and natural history of the Moon itself, LRO continues to deliver state-of-the-art information about a place that almost every human being has pondered as it drifts through our skies and our collective imaginations.
  • Water on the Moon
    2013.06.03
    Since the 1960’s, scientists have suspected that frozen water could survive in cold, dark craters at the Moon’s poles. While previous lunar missions have detected hints of water on the Moon, new data from the Lunar Reconnaissance Orbiter (LRO) pinpoints areas near the south pole where water is likely to exist. The key to this discovery is hydrogen, the main ingredient in water: LRO uses its Lunar Exploration Neutron Detector, or LEND, to measure how much hydrogen is trapped within the lunar soil. By combining years of LEND data, scientists see mounting evidence of hydrogen-rich areas near the Moon’s south pole, strongly suggesting the presence of frozen water.
  • The Moon's Permanently Shadowed Regions
    2013.03.06
    As you watch the Moon over the course of a month, you'll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun's light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA's Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail.