This illustration shows a star behind a shattered comet. Observations of the star KIC 8462852 by NASA's Kepler and Spitzer space telescopes suggest that its unusual light signals are likely from dusty comet fragments, which blocked the light of the star as they passed in front of it in 2011 and 2013. The comets are thought to be traveling around the star in a very long, eccentric orbit.

Observations from NASA's Spitzer Space Telescope reveal new information about the structure of 2011 MD, a small asteroid being considered by NASA for its proposed Asteroid Redirect Mission, or ARM. Spitzer's infrared images helped reveal that this asteroid consists of about two-thirds empty space. There are several possible structures for such an asteroid, two of which are illustrated here: a loosely clumped group of boulders (left) and a solid clump loosely packed with fine debris (right).

This image of asteroid 2011 MD was taken by NASA's Spitzer Space Telescope in Feb. 2014, over a period of 20 hours. The long observation, taken in infrared light, was needed to pick up the faint signature of the small asteroid (center of frame). The Spitzer observations helped narrow down the size of the space rock to roughly 20 feet (6 meters), making it one of a few candidates for NASA's proposed Asteroid Redirect Mission for which sizes are approximately known. This image was taken by Spitzer's Infrared Array Camera at a wavelength of 4.5 microns.

Asteroids can differ in the degree of porosity, or the amount of empty space that makes up their structures. At one end of the spectrum is a single solid rock and, at the other end, is a pile of rubble held together by gravity. Observations from NASA's Spitzer Space Telescope, taken in infrared light, have helped to reveal that a small asteroid called 2011 MD is made-up of two-thirds empty space, which means it has essentially the same density as water.

Observations of infrared light coming from asteroids provide a better estimate of their true sizes than visible-light measurements. This diagram illustrates why. At left, are three asteroids with different sizes and compositions. Even though they are different, they can appear to the same to a visible-light telescope because they reflect the same amount of sunlight. It's impossible to know their sizes. For example, the small, white asteroid has a more reflective surface so it can appear to have the same brightness as a larger, dark asteroid. The same is true of a shiny penny and larger piece of dull copper -- they could, in some circumstances, reflect the same amount of total light. The right side of the illustration shows what happens in the infrared. When an asteroid is hit with sunlight, it radiates some of that back as infrared light. The amount of infrared light that comes off an asteroid thus depends on the size of its exposed surface area. When infrared and visible-light observations are combined, the reflectivity of a surface, or its albedo, can also be determined.

Observations from NASA's Spitzer Space Telescope reveal new information about the structure of 2011 MD, a small asteroid being considered by NASA for its proposed Asteroid Redirect Mission, or ARM. Spitzer's infrared images helped reveal that this asteroid consists of about two-thirds empty space. One possible structure for such an asteroid is illustrated here: a loosely clumped group of boulders.

Observations from NASA's Spitzer Space Telescope reveal new information about the structure of 2011 MD, a small asteroid being considered by NASA for its proposed Asteroid Redirect Mission, or ARM. Spitzer's infrared images helped reveal that this asteroid consists of about two-thirds empty space. One possible structure for such an asteroid is illustrated here: a solid clump loosely packed with fine debris.

NASA's Spitzer Space Telescope has taken on a new role for asteroid-hunting astronomers. A new software tool lets astronomers quickly comb through existing datasets to recover detections of newly-discovered asteroids from its 10+ year archive of observations. This "precovery" process extrapolates the path of a known asteroid back in time and checks to see whether at some point it may have serendipitously appeared in any of Spitzer's previous observations. Making dense archives such as Spitzer's easily accessible should add to the wealth of small Solar System body information obtained by asteroid-hunting missions like NEOWISE. For instance, observations of objects at varying locations in their orbits, where sunlight glints off them at distinct angles like the phases of the Moon, can reveal characteristics about their shapes and textures. Additionally, seeing an object at different points in time also lends a hand in calculating its trajectory through space.

With the help of NASA's Spitzer Space Telescope, astronomers have discovered that what was thought to be a large asteroid called Don Quixote is in fact a comet. The left image shows Don Quixote's coma and tail -- features of comets -- as revealed in infrared light by Spitzer. The coma appears as a faint glow around the center of the body, caused by dust and gas. The tail, which appears more clearly in the right image, points towards the right-hand side of Don Quixote, into the direction opposite of the sun. The right image represents a more elaborate image processing step, in which the glow of the coma has been removed based on a model comet coma. Bright speckles around Don Quixote are background stars; the horizontal bar covers image artifacts caused by the image processing.

With the help of NASA's Spitzer Space Telescope, astronomers have discovered that what was thought to be a large asteroid called Don Quixote is in fact a comet. Don Quixote's coma and tail -- features of comets -- as revealed in infrared light by Spitzer. The coma appears as a faint glow around the center of the body, caused by dust and gas. The tail points towards the right-hand side of Don Quixote, into the direction opposite of the sun.

With the help of NASA's Spitzer Space Telescope, astronomers have discovered that what was thought to be a large asteroid called Don Quixote is in fact a comet. This image represents a more elaborate image processing step, in which the glow of the coma has been removed based on a model comet coma. Bright speckles around Don Quixote are background stars; the horizontal bar covers image artifacts caused by the image processing.

These images from NASA's Spitzer Space Telescope of C/2012 S1 (Comet ISON) were taken on June 13, when ISON was 310 million miles (about 500 million kilometers) from the sun. The images were taken with the telescope's infrared array camera at two different near-infrared wavelengths, 3.6 and 4.5 microns (the representational colors shown were selected to enhance visibility). The 3.6-micron image on the left shows a tail of fine rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds towards the sun (the tail points away from the sun). The image on the right side shows the 4.5-micron image with the 3.6-micron image information (dust) removed, and reveals a very different round structure -- the first detection of a neutral gas atmosphere surrounding ISON. In this case, it is most likely created by carbon dioxide that is fizzing from the surface of the comet at a rate of about 2.2 million pounds (1 million kilograms) a day. Comet ISON (officially known as C/2012 S1) is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. ISON will pass within 724,000 miles (1.2 million kilometers) of the sun on Nov. 28, making it a sungrazer comet that will evaporate its ices and even its rocky dust near perihelion, revealing even more of the comets composition. NASA is bringing to bear a vast fleet of spacecraft, instruments, and space- and Earth-based telescopes to study this rarely-seen type of comet over the next year. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. The complete list of observers is: C.M. Lisse, R.J. Vervack, and H.A. Weaver, Johns Hopkins University Applied Physics Laboratory; J.M. Bauer, Jet Propulsion Laboratory/Caltech; Y.R. Fernandez, University of Central Florida; M.S.P. Kelley, University of Maryland; M.M. Knight, Lowell Observatory; D. Hines, Space Telescope Science Institute; J-Y Li, Planetary Science Institute; W. Reach, USRA/SOFIA; M. L. Sitko, University of Cincinnati; P. A. Yanamandra-Fisher, SSI; K.J. Meech and J. Rayner, University of Hawaii.

This artist's concept illustrates an asteroid belt around the bright star Vega. Evidence for this warm ring of debris was found using NASA's Spitzer Space Telescope, and the European Space Agency's Herschel Space Observatory, in which NASA plays an important role.

This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Evidence for this barrage comes from NASA's Spitzer Space Telescope, whose infrared detectors picked up indications that one or more comets was recently torn to shreds after colliding with a rocky body. In this artist's conception, one such giant comet is shown smashing into a rocky planet, flinging ice- and carbon-rich dust into space, while also smashing water and organics into the surface of the planet. A glowing red flash captures the moment of impact on the planet. Yellow-white Eta Corvi is shown to the left, with still more comets streaming toward it. Spitzer detected spectral signatures of water ice, organics and rock around Eta Corvi -- key ingredients of comets. This is the first time that evidence for such a comet storm has been seen around another star. Eta Corvi is just about the right age, about one billion years old, to be experiencing a bombardment of comets akin to what occurred in our own solar system at 600 to 800 millions years of age, termed the Late Heavy Bombardment. Scientists say the Late Heavy Bombardment was triggered in our solar system by the migration of our outer planets, which jostled icy comets about, sending some of them flying inward. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life.

This image, taken by NASA's Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of Eros, an asteroid with an orbit that takes it somewhat close to Earth. NASA's Spitzer Space Telescope observed Eros and dozens of other near-Earth asteroids as part of an ongoing survey to study their sizes and compositions using infrared light.

NASA's Spitzer Space Telescope set its infrared eyes upon the dusty remains of shredded asteroids around several dead stars. This artist's concept illustrates one such dead star, or "white dwarf," surrounded by the bits and pieces of a disintegrating asteroid. These observations help astronomers better understand what rocky planets are made of around other stars. Asteroids are leftover scraps of planetary material. They form early on in a star's history when planets are forming out of collisions between rocky bodies. When a star like our sun dies, shrinking down to a skeleton of its former self called a white dwarf, its asteroids get jostled about. If one of these asteroids gets too close to the white dwarf, the white dwarf's gravity will chew the asteroid up, leaving a cloud of dust. Spitzer's infrared detectors can see these dusty clouds and their various constituents. So far, the telescope has identified silicate minerals in the clouds polluting eight white dwarfs. Because silicates are common in our Earth's crust, the results suggest that planets similar to ours might be common around other stars.

This artist's conception shows the closest known planetary system to our own, called Epsilon Eridani. Observations from NASA's Spitzer Space Telescope show that the system hosts two asteroid belts, in addition to previously identified candidate planets and an outer comet ring. Epsilon Eridani is located about 10 light-years away in the constellation Eridanus. It is visible in the night skies with the naked eye. The system's inner asteroid belt appears as the yellowish ring around the star, while the outer asteroid belt is in the foreground. The outermost comet ring is too far out to be seen in this view, but comets originating from it are shown in the upper right corner. Astronomers think that each of Epsilon Eridani's asteroid belts could have a planet orbiting just outside it, shepherding its rocky debris into a ring in the same way that Jupiter helps keep our asteroid belt confined. The planet near the inner belt was previously identified in 2000 via the radial velocity, or "star wobble," technique, while the planet near the outer belt was inferred when Spitzer discovered the belt. The inner belt orbits at a distance of about 3 astronomical units from its star -- or about the same position as the asteroid belt in our own solar system (an astronomical unit is the distance between Earth and our sun). The second asteroid belt lies at about 20 astronomical units from the star, or a position comparable to Uranus in our solar system. The outer comet ring orbits from 35 to 90 astronomical units from the star; our solar system's analogous Kuiper Belt extends from about 30 to 50 astronomical units from the sun.

NASA's Spitzer Space Telescope captured the picture on the left of comet Holmes in March 2008, five months after the comet suddenly erupted and brightened a millionfold overnight. The contrast of the picture has been enhanced on the right to show the anatomy of the comet. Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes mysteriously exploded as it approached the asteroid belt. Astronomers still do not know the cause of these eruptions. Spitzer's infrared picture at left reveals fine dust particles that make up the outer shell, or coma, of the comet. The nucleus of the comet is within the bright whitish spot in the center, while the yellow area shows solid particles that were blown from the comet in the explosion. The comet is headed away from the sun, which lies beyond the right-hand side of the picture. The contrast-enhanced picture on the right shows the comet's outer shell, and strange filaments, or streamers, of dust. The streamers and shell are a yet another mystery surrounding comet Holmes. Scientists had initially suspected that the streamers were small dust particles ejected from fragments of the nucleus, or from hyerpactive jets on the nucleus, during the October 2007 explosion. If so, both the streamers and the shell should have shifted their orientation as the comet followed its orbit around the sun. Radiation pressure from the sun should have swept the material back and away from it. But pictures of comet Holmes taken by Spitzer over time show the streamers and shell in the same configuration, and not pointing away from the sun. The observations have left astronomers stumped. The horizontal line seen in the contrast-enhanced picture is a trail of debris that travels along with the comet in its orbit. The Spitzer picture was taken with the spacecraft's multiband imaging photometer at an infrared wavelength of 24 microns.

NASA's Spitzer Space Telescope captured the picture on the left of comet Holmes in March 2008, five months after the comet suddenly erupted and brightened a millionfold overnight. The contrast of the picture has been enhanced on the right to show the anatomy of the comet. Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes mysteriously exploded as it approached the asteroid belt. Astronomers still do not know the cause of these eruptions. Spitzer's infrared picture at left reveals fine dust particles that make up the outer shell, or coma, of the comet. The nucleus of the comet is within the bright whitish spot in the center, while the yellow area shows solid particles that were blown from the comet in the explosion. The comet is headed away from the sun, which lies beyond the right-hand side of the picture. The contrast-enhanced picture on the right shows the comet's outer shell, and strange filaments, or streamers, of dust. The streamers and shell are a yet another mystery surrounding comet Holmes. Scientists had initially suspected that the streamers were small dust particles ejected from fragments of the nucleus, or from hyerpactive jets on the nucleus, during the October 2007 explosion. If so, both the streamers and the shell should have shifted their orientation as the comet followed its orbit around the sun. Radiation pressure from the sun should have swept the material back and away from it. But pictures of comet Holmes taken by Spitzer over time show the streamers and shell in the same configuration, and not pointing away from the sun. The observations have left astronomers stumped. The horizontal line seen in the contrast-enhanced picture is a trail of debris that travels along with the comet in its orbit. The Spitzer picture was taken with the spacecraft's multiband imaging photometer at an infrared wavelength of 24 microns.

NASA's Spitzer Space Telescope captured the picture on the left of comet Holmes in March 2008, five months after the comet suddenly erupted and brightened a millionfold overnight. The contrast of the picture has been enhanced on the right to show the anatomy of the comet. Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes mysteriously exploded as it approached the asteroid belt. Astronomers still do not know the cause of these eruptions. Spitzer's infrared picture at left reveals fine dust particles that make up the outer shell, or coma, of the comet. The nucleus of the comet is within the bright whitish spot in the center, while the yellow area shows solid particles that were blown from the comet in the explosion. The comet is headed away from the sun, which lies beyond the right-hand side of the picture. The contrast-enhanced picture on the right shows the comet's outer shell, and strange filaments, or streamers, of dust. The streamers and shell are a yet another mystery surrounding comet Holmes. Scientists had initially suspected that the streamers were small dust particles ejected from fragments of the nucleus, or from hyerpactive jets on the nucleus, during the October 2007 explosion. If so, both the streamers and the shell should have shifted their orientation as the comet followed its orbit around the sun. Radiation pressure from the sun should have swept the material back and away from it. But pictures of comet Holmes taken by Spitzer over time show the streamers and shell in the same configuration, and not pointing away from the sun. The observations have left astronomers stumped. The horizontal line seen in the contrast-enhanced picture is a trail of debris that travels along with the comet in its orbit. The Spitzer picture was taken with the spacecraft's multiband imaging photometer at an infrared wavelength of 24 microns.

These artist's concepts of Tempel 1 simulate an optical view of the comet (left), next to the simulated infrared view (right). The images illustrate the comet's shape, reflectivity, rotation rate and surface temperature, based on information from NASA's Hubble Space Telescope and Spitzer Space Telescope. Measurements from the Great Observatories indicate that the comet is a matte black object roughly 14 by 4 kilometers (8.7 by 2.5 miles), or about one-half the size of Manhattan. Spitzer detects the comet's infrared energy or heat, depicted by the reddish glow. The sunlit side of the nucleus is glowing warmly, and the nightside is about the temperature of deep space.

This graph of data from NASA's Spitzer Space Telescope demonstrates that the dust around a nearby star called HD 69830 (upper line) has a very similar composition to that of Comet Hale-Bopp. Spitzer spotted large amounts of this dust in the inner portion of the HD 69830 system. The bumps and dips seen in these data, or spectra, represent the "fingerprints" of various minerals. Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. These particular spectra reveal the presence of the silicate mineral called olivine, and more specifically, a type of olivine called forsterite, which is pictured in the inset box. Forsterite is a bright-green gem found on Earth, on the "Green Sand Beach" of Hawaii among other places; and in space, in comets and asteroids. Because the dust around HD 69830 has a very similar make-up to that of Comet Hale-Bopp, astronomers speculate that it might be coming from a giant comet nearly the size of Pluto. Such a comet may have been knocked into the inner solar system of HD 69830, where it is now leaving in its wake a trail of evaporated dust. Nonetheless, astronomers say the odds that Spitzer has caught a "super-comet" spiraling in toward its star -- an unusual and relatively short-lived event -- are slim. Instead, they favor the theory that the observed dust is actually the result of asteroids banging together in a massive asteroid belt. The data of HD 69830's dust were taken by Spitzer's infrared spectrograph. The data of Comet Hale-Bopp were taken by the European Space Agency's Infrared Observatory Satellite. The picture of forsterite comes courtesy of Dr. George Rossman, California Institute of Technology, Pasadena.