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The Sun is stirring from its latest slumber. As sunspots and flares, signs of a new solar cycle, bubble from the Sun’s surface, scientists are anticipating a flurry of solar activity over the next few years. Roughly every 11 years, at the height of this cycle, the Sun’s magnetic poles flip—on Earth, that’d be like the North and South Poles’ swapping places every decade—and the Sun transitions from sluggish to active and stormy. At its quietest, the Sun is at solar minimum; during solar maximum, the Sun blazes with bright flares and solar eruptions. In this video, view the Sun's disk from our space telescopes as it transitions from minimum to maximum in the solar cycle.
Music credit: "Observance" by Andrew Michael Britton [PRS], David Stephen Goldsmith [PRS] from Universal Production Music
NASA and its partner’s satellites had a unique vantage point to watch the eclipse. Several Sun-watching satellites were in a position to see the Moon cross in front of the Sun, while many Earth-observing satellites – and NASA’s Lunar Reconnaissance Orbiter, which typically images the Moon’s landscape – captured images of the Moon’s shadow on Earth’s surface.
See more and download content at https://go.nasa.gov/2x7b8kf
Imagery provided by:
SDO
NASA/SDO
ISS
NASA/ISS
SOHO
inside image credit: Solar Dynamics Observatory, LMSAL and NASA’s GSFC;
Middle image: Jay Pasachoff, Ron Dantowitz, Christian Lockwood, and the Williams College Eclipse Expedition/NSF/National Geographic
Outside image credit: LASCO from NRL on SOHO from ESA/NASA
Hinode
Image credit: JAXA/NASA
GOES
Image credit: NOAA/NASA’s GOES-16
NOAA’s DSCOVR
Image credit: NASA EPIC Team
Terra
Image credit: NASA Earth Observatory images by Joshua Stevens and Jesse Allen, using MODIS data from the Land Atmosphere Near real-time Capability for EOS (LANCE) and EOSDIS/Rapid Response
Suomi NPP
Image credit: NASA Earth Observatory image by Joshua Stevens and Jesse Allen, using VIIRS data from the University of Wisconsin’s Space Science and Engineering Center Direct Broadcast system.
IRIS
Image credit: LMSAL/NASA, Bart De Pontieu
LRO
Image credit: NASA/GSFC/Arizona State University
The 2016 Mercury transit occurred on May 9th, between about 7:12 a.m. and 2:42 p.m. EDT.
The images in this video are from NASA's Solar Dynamics Observatory, or SDO.
Transits provide a great opportunity to study the way planets and stars move in space– information that has been used throughout the ages to better understand the solar system and which still helps scientists today calibrate their instruments.
Though SDO sees dozens of Earth eclipses and several lunar transits each year, this is the first time ever that the two have coincided.
SDO’s orbit usually gives us unobstructed views of the sun, but Earth’s revolution around the sun means that SDO’s orbit passes behind Earth twice each year, for two to three weeks at a time. During these phases, Earth blocks SDO’s view of the sun for anywhere from a few minutes to over an hour once each day.
Earth’s outline looks fuzzy, while the moon’s is crystal-clear. This is because—while the planet itself completely blocks the sun's light—Earth’s atmosphere is an incomplete barrier, blocking different amounts of light at different altitudes. However, the moon has no atmosphere, so during the transit we can see the crisp edges of the moon's horizon.
Note in the pictures how crisp the horizon is on the moon, a reflection of the fact that the moon has no atmosphere around it to distort the light from the sun.
The sun emitted a mid-level solar flare, peaking at 11:11 a.m. EST on Jan. 30, 2014. Images of the flare were captured by NASA's Solar Dynamics Observatory, or SDO, shortly after the observatory witnessed a lunar transit. The black disk of the moon can be seen in the lower right of the images.
This flare is classified as an X4.9-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.
To have a record of such an intense flare from so many observatories is unprecedented. Such research can help scientists better understand what catalyst sets off these large explosions on the sun. Perhaps we may even some day be able to predict their onset and forewarn of the radio blackouts solar flares can cause near Earth – blackouts that can interfere with airplane, ship and military communications.
All Video and Image Credit: NASA/SDO
In reality, the sun is not made of fire, but of something called plasma: particles so hot that their electrons have boiled off, creating a charged gas that is interwoven with magnetic fields.
These images were captured on Sept. 29-30, 2013, by NASA's Solar Dynamics Observatory, or SDO, which constantly observes the sun in a variety of wavelengths.
Different wavelengths help capture different aspect of events in the corona. The red images shown in the movie help highlight plasma at temperatures of 90,000° F and are good for observing filaments as they form and erupt. The yellow images, showing temperatures at 1,000,000° F, are useful for observing material coursing along the sun's magnetic field lines, seen in the movie as an arcade of loops across the area of the eruption. The browner images at the beginning of the movie show material at temperatures of 1,800,000° F, and it is here where the canyon of fire imagery is most obvious. By comparing this with the other colors, one sees that the two swirling ribbons moving farther away from each other are, in fact, the footprints of the giant magnetic field loops, which are growing and expanding as the filament pulls them upward.
A new NASA movie of the sun based on data from NASA's Solar Dynamics Observatory, or SDO, shows the wide range of wavelengths – invisible to the naked eye – that the telescope can view. SDO converts the wavelengths into an image humans can see, and the light is colorized into a rainbow of colors.
As the colors sweep around the sun in the movie, viewers should note how different the same area of the sun appears. This happens because each wavelength of light represents solar material at specific temperatures. Different wavelengths convey information about different components of the sun's surface and atmosphere, so scientists use them to paint a full picture of our constantly changing and varying star.
Yellow light of 5800 angstroms, for example, generally emanates from material of about 10,000 degrees F (5700 degrees C), which represents the surface of the sun. Extreme ultraviolet light of 94 angstroms, which is typically colorized in green in SDO images, comes from atoms that are about 11 million degrees F (6,300,000 degrees C) and is a good wavelength for looking at solar flares, which can reach such high temperatures. By examining pictures of the sun in a variety of wavelengths – as is done not only by SDO, but also by NASA's Interface Region Imaging Spectrograph, NASA's Solar Terrestrial Relations Observatory and the European Space Agency/NASA Solar and Heliospheric Observatory — scientists can track how particles and heat move through the sun's atmosphere.
Eight hours later, on July 19, the same region flared again. This time the flux rope's connection to the sun was severed, and the magnetic fields escaped into space, dragging billions of tons of solar material along for the ride — a classic CME.
More than just gorgeous to see, such direct observation offers one case study on how this crucial kernel at the heart of a CME forms. Such flux ropes have been seen in images of CMEs as they fly away from the sun, but it's never been known — indeed, has been strongly debated — whether the flux rope formed before or in conjunction with a CME's launch. This case shows a clear-cut example of the flux rope forming ahead of time.
Watch this video on YouTube.
On July 19, 2012, an eruption occurred on the sun that produced all three. A moderately powerful solar flare exploded on the sun's lower right hand limb, sending out light and radiation. Next came a CME, which shot off to the right out into space. And then, the sun treated viewers to one of its dazzling magnetic displays — a phenomenon known as coronal rain.
Over the course of the next day, hot plasma in the corona cooled and condensed along strong magnetic fields in the region. Magnetic fields, themselves, are invisible, but the charged plasma is forced to move along the lines, showing up brightly in the extreme ultraviolet wavelength of 304 angstroms, which highlights material at a temperature of about 50,000 Kelvin. This plasma acts as a tracer, helping scientists watch the dance of magnetic fields on the sun, outlining the fields as it slowly falls back to the solar surface.
The footage in this video was collected by the Solar Dynamics Observatory's AIA instrument. SDO collected one frame every 12 seconds, and the movie plays at 30 frames per second, so each second in this video corresponds to 6 minutes of real time. The video covers 12:30 a.m. EDT to 10:00 p.m. EDT on July 19, 2012.
Watch this video on YouTube.
SDO's Atmospheric Imaging Assembly (AIA) captures a shot of the sun every 12 seconds in 10 different wavelengths. The images shown here are based on a wavelength of 171 angstroms, which is in the extreme ultraviolet range and shows solar material at around 600,000 Kelvin. In this wavelength it is easy to see the sun's 25-day rotation as well as how solar activity has increased over three years.
During the course of the video, the sun subtly increases and decreases in apparent size. This is because the distance between the SDO spacecraft and the sun varies over time. The image is, however, remarkably consistent and stable despite the fact that SDO orbits the Earth at 6,876 miles per hour and the Earth orbits the sun at 67,062 miles per hour.
Such stability is crucial for scientists, who use SDO to learn more about our closest star. These images have regularly caught solar flares and coronal mass ejections in the act, types of space weather that can send radiation and solar material toward Earth and interfere with satellites in space. SDO's glimpses into the violent dance on the sun help scientists understand what causes these giant explosions — with the hopes of some day improving our ability to predict this space weather.
The four wavelength view at the end of the video shows light at 4500 angstroms, which is basically the visible light view of the sun, and reveals sunspots; light at 193 angstroms which highlights material at 1 million Kelvin and reveals more of the sun's corona; light at 304 angstroms which highlights material at around 50,000 Kelvin and shows features in the transition region and chromosphere of the sun; and light at 171 angstroms.
Noteworthy events that appear briefly in the main sequence of this video:
00:30;24 Partial eclipse by the moon
00:31;16 Roll maneuver
01:11;02 August 9, 2011 X6.9 Flare, currently the largest of this solar cycle
01:28;07 Comet Lovejoy, December 15, 2011
01:42;29 Roll Maneuver
01:51;07 Transit of Venus, June 5, 2012
02:28;13 Partial eclipse by the moon
Watch this video on YouTube.
Such eruptions soon leave SDO's field of view, but other satellites in NASA's Heliophysics fleet can pick them up, tracking such space weather to determine if they are headed toward Earth or spacecraft near other planets. With advance warning, many space assets can be put into safe mode and protect themselves from the effects of such particle radiation.
In addition to the images captured by SDO, the May 1, 2013 CME was also observed by the ESA/NASA Solar and Heliospheric Observatory (SOHO). SOHO houses two overlapping coronagraphs—telescopes where the bright sun is blocked by a disk so it doesn't overpower the fainter solar atmosphere—and they both saw the CME continue outward. The LASCO C2 coronagraph shows the region out to about 2.5 million miles. The LASCO C3 coronagraph expands even farther out to around 13.5 million miles. Both of these instruments show the CME as it expands and becomes fainter on its trip away from the sun.
NASA's Solar Terrestrial Relations Observatory (STEREO) Ahead satellite saw the eruption from a very different angle. It, along with its twin STEREO Behind, is orbiting at a similar distance as Earth. STEREO-A orbits slightly faster than Earth and STEREO-B orbits slightly slower. Currently, STEREO-A is more than two-thirds of the way to being directly behind the sun, and has a view of the far side of the sun. From this perspective, the CME came off the right side of the sun. STEREO has an extreme ultraviolet camera similar to SDO's, but it also has coronagraphs like SOHO. As a result, using its two inner coronagraphs, it was able to track the CME from the solar surface out to 6.3 million miles.
Working together, such missions provide excellent coverage of a wide variety of solar events, a wealth of scientific data—and lots of beautiful imagery.
Watch this video on YouTube.
On May 12, 2013, the sun emitted a significant solar flare, peaking at 10 p.m. EDT. This flare is classified as an X1.7, making it the first X-class flare of 2013. The flare was also associated with another solar phenomenon, called a coronal mass ejection (CME) that can send solar material out into space. This CME was not Earth-directed.
The May 12 flare was also associated with a coronal mass ejection, another solar phenomenon that can send billions of tons of solar particles into space, which can affect electronic systems in satellites and on the ground. Experimental NASA research models show that the CME left the sun at 745 miles per second and is not Earth-directed, however its flank may pass by the STEREO-B and Spitzer spacecraft, and their mission operators have been notified. If warranted, operators can put spacecraft into safe mode to protect the instruments from solar material. There is some particle radiation associated with this event, which is what can concern operators of interplanetary spacecraft since the particles can trip computer electronics on board.
Magnetic reconnection happens when magnetic field lines come together, break apart, and then exchange partners, snapping into new positions and releasing a jolt of magnetic energy. This process lies at the heart of giant explosions on the sun such as solar flares and coronal mass ejections, which can fling radiation and particles across the solar system.
Magnetic field lines, themselves, are invisible, but the sun's charged plasma particles course along their length. Space telescopes can see that material appearing as bright lines looping and arcing through the sun’s atmosphere, and so map out the presence of magnetic field lines.
Looking at a series of images from the Solar Dynamics Observatory (SDO), scientists saw two bundles of field lines move toward each other, meet briefly to form what appeared to be an “X” and then shoot apart with one set of lines and its attendant particles leaping into space and one set falling back down onto the sun.
To confirm what they were seeing, the scientists turned to a second NASA spacecraft, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). RHESSI collects spectrograms, a kind of data that can show where exceptionally hot material is present in any given event on the sun. RHESSI showed hot pockets of solar material forming above and below the reconnection point, an established signature of such an event. By combining the SDO and RHESSI data, the scientists were able to describe the process of what they were seeing, largely confirming previous models and theories, while revealing new, three-dimensional aspects of the process.
Being so close to the sun is very hard on comets for many reasons. They are subjected to a lot of solar radiation which boils off their water or other volatiles. The physical push of the radiation and the solar wind also helps form the tails. And as they get closer to the sun, the comets experience extremely strong tidal forces, or gravitational stress. In this hostile environment, many sungrazers do not survive their trip around the sun. Although they don't actually crash into the solar surface, the sun is able to destroy them anyway.
Many sungrazing comets follow a similar orbit, called the Kreutz Path, and collectively belong to a population called the Kreutz Group. In fact, close to 85% of the sungrazers seen by the SOHO satellite are on this orbital highway. Scientists think one extremely large sungrazing comet broke up hundreds, or even thousands, of years ago, and the current comets on the Kreutz Path are the leftover fragments of it. As clumps of remnants make their way back around the sun, we experience a sharp increase in sungrazing comets, which appears to be going on now. Comet Lovejoy, which reached perihelion on December 15, 2011 is the best known recent Kreutz-group sungrazer. And so far, it is the only one that NASA's solar-observing fleet has seen survive its trip around the sun.
Comet ISON, an upcoming sungrazer with a perihelion of 730,000 miles on November 28, 2013, is not on the Kreutz Path. In fact, ISON's orbit suggests that it may gain enough momentum to escape the solar system entirely, and never return. Before it does so, it will pass within about 40 million miles from Earth on December 26th. Assuming it survives its trip around the sun.
The images here show an unfiltered image from the sun next to one that has been processed using a gradient filter. Note how the coronal loops are sharp and defined, making them all the more easy to study. On the other hand, gradients also make great art. Watch the movie to see how the sharp loops on the sun next to the more fuzzy areas in the lower solar atmosphere provide a dazzling show.
About an hour later, at 8:14 PM ET, March 6, the same region let loose an X1.3 class flare. ?An X1 is 5 times smaller than an X5 flare.
These X-class flares erupted from an active region named AR 1429 that rotated into view on March 2. ?Prior to this, the region had already produced numerous M-class and one X-class flare. ?The region continues to rotate across the front of the sun, so the March 6 flare was more Earthward facing than the previous ones. ?It triggered a temporary radio blackout on the sunlit side of Earth that interfered with radio navigation and short wave radio.
In association with these flares, the sun also expelled two significant coronal mass ejections (CMEs), which are traveling faster than 600 miles a second and may arrive at Earth in the next few days. ?In the meantime, the CME associated with the X-class flare from March 4 has dumped solar particles and magnetic fields into Earth's atmosphere and distorted Earth's magnetic fields, causing a moderate geomagnetic storm, rated a G2 on a scale from G1 to G5. ?Such storms happen when the magnetic fields around Earth rapidly change strength and shape. ?A moderate storm usually causes aurora and may interfere with high frequency radio transmission near the poles. ?This storm is already dwindling, but the Earth may experience another enhancement if the most recent CMEs are directed toward and impact Earth.
In addition, last night's flares have sent solar particles into Earth's atmosphere, producing a moderate solar energetic particle event, also called a solar radiation storm. These particles have been detected by NASA's SOHO and STEREO spacecraft, and NOAA's GOES spacecraft. ?At the time of writing, this storm is rated an S3 on a scale that goes up to S5. ?Such storms can interfere with high frequency radio communication.
Besides the August 2011 X-class flare, the last time the sun sent out flares of this magnitude was in 2006. ?There was an X6.5 on December 6, 2006 and an X9.0 on December 5, 2006. Like the most recent events, those two flares erupted from the same region on the sun, which is a common occurrence.
On June 5 2012, SDO collected images of the rarest predictable solar event—the transit of Venus across the face of the sun. This event lasted approximately 6 hours and happens in pairs eight years apart, which are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117.
The videos and images displayed here are constructed from several wavelengths of extreme ultraviolet light and a portion of the visible spectrum. The red colored sun is the 304 angstrom ultraviolet, the golden colored sun is 171 angstrom, the magenta sun is 1700 angstrom, and the orange sun is filtered visible light. 304 and 171 show the atmosphere of the sun, which does not appear in the visible part of the spectrum.
More information, of course, requires more complex visualizations and occasionally such images are not just informative, but beautiful too.
Such is the case with a new technique created by Nicholeen Viall, a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. She creates images of the sun reminiscent of Van Gogh, with broad strokes of bright color splashed across a yellow background. But it's science, not art. The color of each pixel contains a wealth of information about the 12-hour history of cooling and heating at that particular spot on the sun. That heat history holds clues to the mechanisms that drive the temperature and movements of the sun's atmosphere, or corona.
To look at the corona from a fresh perspective, Viall created a new kind of picture, making use of the high resolution provided by NASA's Solar Dynamics Observatory (SDO). SDO's Atmospheric Imaging Assembly (AIA) provides images of the sun in 10 different wavelengths, each approximately corresponding to a single temperature of material. Therefore, when one looks at the wavelength of 171 angstroms, for example, one sees all the material in the sun's atmosphere that is a million degrees Kelvin. By looking at an area of the sun in different wavelengths, one can get a sense of how different swaths of material change temperature. If an area seems bright in a wavelength that shows a hotter temperature an hour before it becomes bright in a wavelength that shows a cooler temperature, one can gather information about how that region has changed over time.
Viall's images show a wealth of reds, oranges, and yellow, meaning that over a 12-hour period the material appear to be cooling. Obviously there must have been heating in the process as well, since the corona isn't on a one-way temperature slide down to zero degrees. Any kind of steady heating throughout the corona would have shown up in Viall's images, so she concludes that the heating must be quick and impulsive — so fast that it doesn't show up in her images. This lends credence to those theories that say numerous nanobursts of energy help heat the corona.
The images here show an unfiltered image from the sun next to one that has been processed using a gradient filter. Note how the coronal loops are sharp and defined, making them all the more easy to study. On the other hand, gradients also make great art. Watch the movie to see how the sharp loops on the sun next to the more fuzzy areas in the lower solar atmosphere provide a dazzling show.
Watch this video on YouTube.
The scientists interviewed are:
Dr. Holly Gilbert, NASA Heliophysicist
Dr. Alex Young, NASA Heliophysicist
Dr. Phil Chamberlin, NASA Research Heliophysicist and SDO Deputy Project Scientist
There are also two short videos created with this interview content. They are available here.
Additional responses to these questions are available upon specific request.
For space weather-related footage, animations, and features, visit the Space Weather gallery.
Part One addresses:
1. What is space weather?
2. What are coronal mass ejections?
3. What are solar flares?
4. What are solar energetic particles?
5. What causes flares and CMEs?
Part Two addresses:
1. Do all flares and CMEs affect the Earth?
2. What happens when a flare or CME hits the Earth?
3. How quickly can we feel the effects of space weather?
4. Why are there more flares and CMEs happening now?
For more information about all these questions and more, visit NASA's Space Weather FAQ.
For individual interview responses to frequently asked space weather questions, go here.
Since scientists know how these kinds of waves — initiated by a Kelvin-Helmholtz instability if you're being technical — disperse energy in the water, they can use this information to better understand the corona. This in turn, may help solve an enduring mystery of why the corona is thousands of times hotter than originally expected.
Kelvin-Helmholtz instabilities occur when two fluids of different densities or different speeds flow by each other. In the case of ocean waves, that's the dense water and the lighter air. As they flow past each other, slight ripples can be quickly amplified into the giant waves loved by surfers. In the case of the solar atmosphere, which is made of a very hot and electrically charged gas called plasma, the two flows come from an expanse of plasma erupting off the sun's surface as it passes by plasma that is not erupting. The difference in flow speeds and densities across this boundary sparks the instability that builds into the waves.
In order to confirm this description, the team developed a computer model to see what takes place in the region. Their model showed that these conditions could indeed lead to giant surfing waves rolling through the corona. Seeing the big waves suggests they can cascade down to smaller forms of turbulence too. Scientists believe that the friction created by turbulence — the simple rolling of material over and around itself — could help add heating energy to the corona. The analogy is the way froth at the top of a surfing wave provides friction that will heat up the wave.
SDO observed the flare's peak at 1:41 AM ET. SDO recorded these images in extreme ultraviolet light that show a very large eruption of cool gas. It is somewhat unique because at many places in the eruption there seems to be even cooler material — at temperatures less than 80,000 K.
This video uses the full-resolution 4096 x 4096 pixel images at a one minute time cadence to provide the highest quality, finest detail version possible.
It is interesting to compare the event in different wavelengths because they each see different temperatures of plasma. See the transcript for more notes on this.
Frames for each wavelength are available on these separate pages: 304, 171, 211, and1700.
Comet Lovejoy survived its encounter with the sun. The second clip shows the comet exiting from behind the right side of the sun, after an hour of travel through its closest approach to the sun. By tracking how the comet interacts with the sun's atmosphere, the corona, and how material from the tail moves along the sun's magnetic field lines, solar scientists hope to learn more about the corona. This movie was filmed by the Solar Dynamics Observatory in 171 angstrom wavelength, which is typically shown in yellow.
Credit: NASA/SDO
Watch engineers talk about what it is like to be an engineer as they build, assemble, integrate, and test the Solary Dynamics Observatory (SDO) soon to be launched in early 2010. If you have a strong tendancy towards science and mathematics, and enjoy working and building things with your hands, then you could also come up with creative solutions, to create something, to do a certain job and do it well.