This image shows a mysterious, background infrared glow captured by NASA's Spitzer Space Telescope. Using Spitzer, researchers were able to detect this background glow, which spreads across the whole sky, by masking out light from galaxies and other known sources of light (the masks are the gray, blotchy marks). The scientists find that this light is coming from stray stars that were torn away from galaxies. When galaxies tangle and merge -- a natural stage of galaxy growth -- stars often get kicked out in the process. The stars are too faint to be seen individually, but Spitzer may be seeing their collective glow.

The image on the left shows a portion of our sky, called the Botes field, in infrared light, while the image on the right shows a mysterious, background infrared glow captured by NASA's Spitzer Space Telescope in the same region of sky. Using Spitzer, researchers were able to detect this background glow, which spreads across the whole sky, by masking out light from galaxies and other known sources of light (the masks are the gray, blotchy marks). The scientists find that this light is coming from stray stars that were torn away from galaxies. When galaxies tangle and merge -- a natural stage of galaxy growth -- stars often get kicked out in the process. The stars are too faint to be seen individually, but Spitzer may be seeing their collective glow.

This graph illustrates the Cepheid period-luminosity relationship, which scientists use to calculate the size, age and expansion rate of the universe. The data shown are from NASA's Spitzer Space Telescope, which has made the most precise measurements yet of the universe's expansion rate by re-calculating the distance to pulsating stars called Cepheids. Cepheids are essential tools in cosmological-distance calculations thanks to what astronomers call their period-luminosity relationship. The timing, or period, of a Cepheid's pulses correlates with its inherit brightness, or luminosity, as shown on this graph. The longer the pulse rate, the more luminous the star. Once astronomers know how luminous a Cepheid is, they can compare that value to how bright they appear on the sky. The objects will appear dimmer and dimmer the farther away they lie. By using a series of Cepheids and even farther objects of a different type, astronomers can determine the size of our universe. Spitzer observed 10 Cepheids in the Milky Way (yellow dots) and 80 in one of our nearest satellite galaxies, the Large Magellanic Cloud (circled dots). At the infrared wavelengths used by the cameras operating on Spitzer, the dimming effects of dust on visible light are virtually non-existent. Moreover the scatter in the points about the Period-Luminosity relation is so small that single stars can be used to determine distances many times more precisely than from the ground and in the optical. These two advantages alone have allowed researchers to use the Spitzer observations of Cepheids to securely recalibrate the size, age and expansion rate of the universe.

A dying star is throwing a cosmic tantrum in this combined image from NASA's Spitzer Space Telescope and the Galaxy Evolution Explorer (GALEX), which NASA has lent to the California Institute of Technology in Pasadena. In death, the star's dusty outer layers are unraveling into space, glowing from the intense ultraviolet radiation being pumped out by the hot stellar core. This object, called the Helix nebula, lies 650 light-years away, in the constellation of Aquarius. Also known by the catalog number NGC 7293, it is a typical example of a class of objects called planetary nebulae. Discovered in the 18th century, these cosmic works of art were erroneously named for their resemblance to gas-giant planets. Planetary nebulae are actually the remains of stars that once looked a lot like our sun. These stars spend most of their lives turning hydrogen into helium in massive runaway nuclear fusion reactions in their cores. In fact, this process of fusion provides all the light and heat that we get from our sun. Our sun will blossom into a planetary nebula when it dies in about five billion years. When the hydrogen fuel for the fusion reaction runs out, the star turns to helium for a fuel source, burning it into an even heavier mix of carbon, nitrogen and oxygen. Eventually, the helium will also be exhausted, and the star dies, puffing off its outer gaseous layers and leaving behind the tiny, hot, dense core, called a white dwarf. The white dwarf is about the size of Earth, but has a mass very close to that of the original star; in fact, a teaspoon of a white dwarf would weigh as much as a few elephants! The glow from planetary nebulae is particularly intriguing as it appears surprisingly similar across a broad swath of the spectrum, from ultraviolet to infrared. The Helix remains recognizable at any of these wavelengths, but the combination shown here highlights some subtle differences. The intense ultraviolet radiation from the white dwarf heats up the expelled layers of gas, which shine brightly in the infrared. GALEX has picked out the ultraviolet light pouring out of this system, shown throughout the nebula in blue, while Spitzer has snagged the detailed infrared signature of the dust and gas in yellow A portion of the extended field beyond the nebula, which was not observed by Spitzer, is from NASA's all-sky Wide-field Infrared Survey Explorer (WISE). The white dwarf star itself is a tiny white pinprick right at the center of the nebula. The brighter purple circle in the very center is the combined ultraviolet and infrared glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust was most likely kicked up by comets that survived the death of their star. Before the star died, its comets, and possibly planets, would have orbited the star in an orderly fashion. When the star ran out of hydrogen to burn, and blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, kicking up an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded. Infrared data from Spitzer for the central nebula is rendered in green (wavelengths of 3.6 to 4.5 microns) and red (8 to 24 microns), with WISE data covering the outer areas in green (3.4 to 4.5 microns) and red (12 to 22 microns). Ultraviolet data from GALEX appears as blue (0.15 to 2.3 microns).

Astronomers using NASAs Spitzer Space Telescope have greatly improved the cosmic distance ladder used to measure the expansion rate of the universe, as well as its size and age. The cosmic distance ladder, symbolically shown here in this artist's concept, is a series of stars and other objects within galaxies that have known distances. By combining these distance measurements with the speeds at which objects are moving away from us, scientists can calculate the expansion rate of the universe, also known as Hubble's constant. Spitzer was able to improve upon past measurements of Hubble's constant due to its infrared vision, which sees through dust to provide better views of variable stars called Cepheids. These pulsating stars are vital "rungs" in the distance ladder. Spitzer observed ten Cepheids in our own Milky Way galaxy and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud. Without the cosmic dust blocking their view at the infrared wavelengths seen by Spitzer, the research team was able to obtain more precise measurements of the stars' apparent brightness, and thus their distances. With these data, the researchers could then tighten up the rungs on the cosmic distant ladder, better determining distances to other galaxies, and calculate a new and improved estimate of our universe's expansion rate. The galaxies used in this composite artwork are all infrared images from Spitzer covering wavelengths of 3.6 microns (blue), 4.5 microns (green), and 8.0 microns (red).

Quasars, as pictured here in this artist's concept, are bright, energetic regions around giant, active black holes in galactic centers. Although immensely powerful and visible across billions of light years, quasars are actually quite tiny, at least compared to an entire galaxy. Quasars span a few light years, and their inner areas casting out high-velocity winds compare roughly in size only to that of our solar system. It takes a beam of light about ten hours to cross that distance. The galaxies that play host to quasars, in contrast, typically span tens of thousands of light years. Surprisingly, the activity in the compact quasar cores is thought to dramatically influence the evolution the surrounding galaxies, and have a significant impact on the properties of massive galaxies seen today. A research team using data from NASA's Spitzer and Hubble Space telescopes have for the first time found a large sample of galaxies during a key early period of galactic evolution when quasars and their host galaxies begin to interact, but before the two have settled down after recent galactic smashups.

With the combined power of NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen. Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes, shining forth from the so-called cosmic dark ages when the universe was just 3.6 percent of its present age. Astronomers relied on gravitational lensing to catch sight of the early, distant galaxy. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. At the center we see light from the newfound galaxy MACS 1149-JD. these visible and infrared light images from Hubble, MACS 1149-JD looks like a dim, red speck. The small galaxy's starlight has been stretched into longer wavelengths, or "redshifted," by the expansion of the universe. MACS 1149-JD's stars originally emitted the infrared light seen here at much shorter, higher-energy wavelengths, such as ultraviolet. The far-off galaxy existed within an important era when the universe transformed from a starless expanse during the dark ages to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, remotest epochs of cosmic history.

With the combined power of NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen. Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes, shining forth from the so-called cosmic dark ages when the universe was just 3.6 percent of its present age. Astronomers relied on gravitational lensing to catch sight of the early, distant galaxy. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. In this image, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times (though it is not readily apparent in this view).

With the combined power of NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen. Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes, shining forth from the so-called cosmic dark ages when the universe was just 3.6 percent of its present age. Astronomers relied on gravitational lensing to catch sight of the early, distant galaxy. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. At the center we see light from the newfound galaxy MACS 1149-JD. these visible and infrared light images from Hubble, MACS 1149-JD looks like a dim, red speck. The small galaxy's starlight has been stretched into longer wavelengths, or "redshifted," by the expansion of the universe. MACS 1149-JD's stars originally emitted the infrared light seen here at much shorter, higher-energy wavelengths, such as ultraviolet. The far-off galaxy existed within an important era when the universe transformed from a starless expanse during the dark ages to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, remotest epochs of cosmic history.

With the combined power of NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen. Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes, shining forth from the so-called cosmic dark ages when the universe was just 3.6 percent of its present age. Astronomers relied on gravitational lensing to catch sight of the early, distant galaxy. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times, bringing the remote object into view. At upper right, a partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the lower right. In these visible and infrared light images from Hubble, MACS 1149-JD looks like a dim, red speck. The small galaxy's starlight has been stretched into longer wavelengths, or "redshifted," by the expansion of the universe. MACS 1149-JD's stars originally emitted the infrared light seen here at much shorter, higher-energy wavelengths, such as ultraviolet. The far-off galaxy existed within an important era when the universe transformed from a starless expanse during the dark ages to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, remotest epochs of cosmic history.

The star cluster NGC 1929 contains massive stars that produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas. The winds and shock waves carve out huge cavities called superbubbles in the surrounding gas. X-rays from Chandra (blue) in this composite image reveal the regions created by these winds and shocks, while infrared data from Spitzer (red) outline where the dust and cooler gas are found. Optical light from an ESO telescope in Chile (yellow) shows where ultraviolet radiation from the young stars is causing the gas to glow.

The galaxy Messier 100, or M100, shows its swirling spiral in this infrared image from NASAs Spitzer Space Telescope. The arcing spiral arms of dust and gas that harbor starforming regions glow vividly when seen in the infrared. is a classic example of a grand design spiral galaxy, with prominent and well-defined spiral arms winding from the hot center, out to the cooler edges of the galaxy. It is located about 55 million light years away from Earth, in the little-known constellation of Coma Berenices, near to the more recognizable Leo. In the center, we can see a prominent ring of hot, bright dust surrounding the inner galactic core. Moving further out, the spiral arms peter out towards the edges of the galaxy, where thick webs of dust dominate. Beyond the edges of the dust clouds, a faint blue glow of stars extends to the edge of the galaxys disk. Two small companion galaxies, known as NGC 4323 and NGC 4328, appear as fuzzy blue blobs on the upper side of M100. These so-called lenticular galaxies are virtually clear of any dust, so they lack any of the red/green glow seen in their bigger neighbor. The shape of M100 is probably being perturbed by the gravity of these galaxies. M100 was discovered in 1781, and is now known to stretch roughly 160,000 light years from one side to the other, making it about one and a half times the size of our own Milky Way galaxy. By studying these infrared images of M100, astronomers can map out the structure of the stars and dust, and study the ways in which galaxies like our Milky Way were formed. M100 is well-known to astronomers because of the five stars that have become supernovae within the galaxy between 1901 and 2006. These exploding stars are extremely useful for helping astronomers to calibrate distance scales in the universe, and to estimate the age of the universe since its creation in the Big Bang. The red regions reveal dust clouds that light up under the illumination of the surrounding stars. The stars themselves shine most brightly at the shorter infrared wavelengths, showing up here in blue. The blue dots covering the entire image are stars that lie between us and M100. Infrared light with wavelengths of 3.6 and 4.5 microns are displayed in blue and green showing primarily the glow from starlight. 8 micron light is rendered in red; the small contribution from starlight at 8 microns was subtracted out from the data to better show the dust structures near the galaxys center.

The galaxy Messier 100, or M100, shows its swirling spiral in this infrared image from NASAs Spitzer Space Telescope. The arcing spiral arms of dust and gas that harbor starforming regions glow vividly when seen in the infrared. M100 is a classic example of a grand design spiral galaxy, with prominent and well-defined spiral arms winding from the hot center, out to the cooler edges of the galaxy. It is located about 55 million light years away from Earth, in the little-known constellation of Coma Berenices, near to the more recognizable Leo. In the center, we can see a prominent ring of hot, bright dust surrounding the inner galactic core. Moving further out, the spiral arms peter out towards the edges of the galaxy, where thick webs of dust dominate. Beyond the edges of the dust clouds, a faint blue glow of stars extends to the edge of the galaxys disk. Two small companion galaxies, known as NGC 4323 and NGC 4328, appear as fuzzy blue blobs on the upper side of M100. These so-called lenticular galaxies are virtually clear of any dust, so they lack any of the red/green glow seen in their bigger neighbor. The shape of M100 is probably being perturbed by the gravity of these galaxies. M100 was discovered in 1781, and is now known to stretch roughly 160,000 light years from one side to the other, making it about one and a half times the size of our own Milky Way galaxy. By studying these infrared images of M100, astronomers can map out the structure of the stars and dust, and study the ways in which galaxies like our Milky Way were formed. M100 is well-known to astronomers because of the five stars that have become supernovae within the galaxy between 1901 and 2006. These exploding stars are extremely useful for helping astronomers to calibrate distance scales in the universe, and to estimate the age of the universe since its creation in the Big Bang. The green regions reveal dust clouds that light up under the illumination of the surrounding stars. The longer infrared wavelengths, which trace the thermal glow of the hottest dust, are overlaid in red. This gives the areas of strongest star formation a reddish/white glow; this is particularly strong in the central ring. The stars themselves shine most brightly at the shorter infrared wavelengths, showing up here in blue. The blue dots covering the entire image are stars that lie between us and M100. Infrared light with wavelengths of 3.6 and 4.5 microns is shown as blue/cyan, showing primarily the glow from starlight. 8 micron light is rendered in green, and 24 micron emission is red, tracing the cooler and warmer components of dust, respectively.

Astronomers using NASA's Spitzer Space Telescope have detected what they believe is an alien world just two-thirds the size of Earth - one of the smallest on record. The exoplanet candidate, known as UCF-1.01, orbits a star called GJ 436, which is located a mere 33 light-years away. UCF-1.01 might be the nearest world to our solar system that is smaller than our home planet. Although probably rocky in composition like Earth, UCF-1.01 would be a terrible place for life. The world orbits scorchingly close to its star, so in all likelihood this planet lacks an atmosphere and might even have a molten surface, as shown in this artist's impression. Evidence for UCF-1.01 turned up when astronomers were studying a known, Neptune-sized exoplanet, called GJ 436b, seen in the background in this image. The identification of nearby small planets may lead to their characterization using future instruments. In this way, worlds like UCF-1.01 might serve as stepping stones to one day finding a habitable, Earth-like exoplanet. Because of GJ 436's proximity to our solar system, the star field around it shares many of our culture's famous cosmic landmarks. To the far left, the constellation of Orion gleams, though in a distorted shape compared to our vantage point on Earth. The red giant Betelgeuse (Orion's right shoulder) and blue Rigel (Orion's left foot) stand out, as well as the three belt stars. From GJ 436's perspective, however, the stars do not align as they do in our sky. The Pleiades star cluster is located to the upper left of UCF-1.01.

This boxy, almost rectangular structure, known as the Retina Nebula or IC 4406, shows its infrared glow in this image from NASA's Spitzer Space Telescope. It is found in the constellation Lupis. Estimates of its distance are somewhat uncertain, placing it anywhere from 2,000 to 5,000 light years away from us. IC 4406 is a planetary nebula, representing the final stage of a star's life. When stars like our sun reach the end of their nuclear fuel burning lifetimes they make one final grab for glory. The outer layers of these stars, which have swollen to something approaching the size of Earth's orbit, get blown into space forming what has been dubbed a "planetary nebula." The expelled gas from the star glows brightly, illuminated by the ultraviolet light from the surviving stellar core, known as a "white dwarf." Astronomers think it is common for stars to lose their material in winds that preferentially blow out along their axes of rotation, effectively carving out a cylindrical, sometimes rod-shaped, cavity. When these structures are viewed from the side, as with IC 4406, they take on a rectangular shape, like a pipe would when seen from the side. The somewhat misleading term "planetary nebula" comes from pioneering astronomer William Herschel. If the pipe of IC 4406 were viewed end-on, it would take the appearance of a strangely-structured ball. After observing a number of such round, fuzzy objects, Herschel thought their appearance was roughly similar to the newly-discovered planet Uranus. Because of that similarity, he applied the description of "planetary" to these nebulae. The term has stuck, even though we now know these stellar remnants have little to do with planets. The only connection is that some of the elements recirculated back into interstellar space may one day end up forming new stars and planetary systems.

How is it that two glowing globs of gas that look completely different can actually be basically the same thing? In the case of planetary nebulae like IC 4406 and NGC 2392, all it may take is a simple shift of perspective, provided here in infrared images taken by NASA's Spitzer Space Telescope. When stars like our sun reach the end of their nuclear fuel burning lifetimes they make one final grab for glory. The outer layers of these stars, which have swollen to something approaching the size of Earth's orbit, get blown into space forming what has been dubbed a "planetary nebula." The expelled gas from the star glows brightly, illuminated by the ultraviolet light from the surviving stellar core, known as a "white dwarf." The two planetary nebulae pictured here look oddly different from one another. IC 4404 takes on a very boxy, rectangular form while NGC 2392 looks more like concentric circles. If they are both the last gasps of dying stars, why would they appear so strikingly different? It appears that stars commonly eject their material in winds that mostly blow out in opposite directions from their poles. This effectively carves out a cavity in the interstellar environment that is roughly cylindrical, or rod-shaped. If you look at this cylindrical cavity from the side, you would expect to see a boxy shape like IC 4406. On the other hand, looking into this cavity from the end, like looking straight into a pipe, you would expect to see something very circular, just like NGC 2392. So even though these two planetary nebulae do not look similar at all, they may just be showing us what a dramatic difference a little change in perspective can bring. The boxy IC 4406 is also known as the "Retina Nebula." It is found in the constellation Lupis. Estimates of its distance are somewhat uncertain, placing it anywhere from 2,000 to 5,000 light years away from us. The rounder NGC 2392 is in the constellation Gemini and is around 3,000 light years away. The pioneering astronomer William Herschel first discovered it in 1787. The somewhat misleading term "planetary nebula" actually comes from Herschel himself. After observing a number of round, fuzzy objects like NGC 2392, he thought their appearance was roughly similar to the newly-discovered planet Uranus. Because of that similarity, he applied the description of "planetary" to these nebulae. The term has stuck, even though we now know these stellar remnants have little to do with planets. The only connection is that some of the elements recirculated back into interstellar space may one day end up forming new stars and planetary systems.

This ball of glowing gas is known as NGC 2392. It is found in the constellation Gemini and is about 3,000 light years away. The pioneering astronomer William Herschel first discovered it in 1787 using an early telescope that revealed very little of the structure we see in this infrared image from NASA's Spitzer Space Telescope. When stars like our sun reach the end of their nuclear fuel burning lifetimes they make one final grab for glory. The outer layers of these stars, which have swollen to something approaching the size of Earth's orbit, get blown into space forming what has been dubbed a "planetary nebula." The expelled gas from the star glows brightly, illuminated by the ultraviolet light from the surviving stellar core, known as a "white dwarf." Astronomers think it is common for stars to lose their material in winds that preferentially blow out along their axes of rotation, effectively carving out a cylindrical, sometimes rod-shaped, cavity. When these structures are viewed end-on, as with NGC 2392, they take on the appearance of a strangely-structured ball. The somewhat misleading term "planetary nebula" actually comes from Herschel himself. After observing a number of round, ball-like objects (including NGC 2392), he thought their appearance was roughly similar to the newly-discovered planet Uranus. Because of that similarity, he applied the description of "planetary" to these nebulae. The term planetary nebula has stuck, even though we now know these stellar remnants have little to do with planets. The only connection is that some of the elements recirculated back into interstellar space may one day end up forming new stars and planetary systems.

Astronomers have uncovered the patterns of light that appear to be from the first stars and galaxies that formed in the universe, hidden within a strip of sky observed by NASAs Spitzer Space Telescope. This panel shows Spitzers typical infrared view of this patch, including foreground stars and a confusion of fainter galaxies, at a wavelength of 4.5 microns. Additional processing of this image reveals faint structures in the background that match just what we would expect for the patterns of clusters for the first galaxies formed in the universe. Even though any particular early galaxy would be too faint to see individually, this technique allows astronomers to better understand what things were like shortly after the Big Bang.

Astronomers have uncovered the patterns of light that appear to be from the first stars and galaxies that formed in the universe, hidden within a strip of sky observed by NASAs Spitzer Space Telescope. These two panels show the same slice of sky in the constellation Botes, dubbed the Extended Groth Strip. The area covered is about 1 by 0.12 degrees in angular extent. The top panel shows Spitzers typical infrared view of this patch, including foreground stars and a confusion of fainter galaxies, at a wavelength of 4.5 microns. In the lower panel, all of the resolved stars and galaxies have been masked out of the image (grey patches), and the remaining background glow has been smoothed and enhanced. This processing reveals a structure too faint to be seen in the original image. The structure of the lower panel matches just what we would expect for the patterns of clusters for the first galaxies formed in the universe. Even though any particular early galaxy would be too faint to see individually, this technique allows astronomers to better understand what things were like shortly after the Big Bang.

Astronomers have uncovered the patterns of light that appear to be from the first stars and galaxies that formed in the universe, hidden within a strip of sky observed by NASAs Spitzer Space Telescope. All of the resolved stars and galaxies have been masked out of the image (grey patches), and the remaining background glow has been smoothed and enhanced. This processing reveals a structure too faint to be seen in the original image. The structure in this image matches just what we would expect for the patterns of clusters for the first galaxies formed in the universe. Even though any particular early galaxy would be too faint to see individually, this technique allows astronomers to better understand what things were like shortly after the Big Bang.

This image of the Pinwheel Galaxy, or M101, combines data in the infrared, visible, ultraviolet and x-rays from four of NASAs space telescopes. This multi-spectral view shows that both young and old stars are evenly distributed along M101s tightly-wound spiral arms. Such composite images allow astronomers to see how features in one part of the spectrum match up with those seen in other parts. It is like seeing with a regular camera, an ultraviolet camera, night-vision goggles and X-Ray vision, all at once! The Pinwheel Galaxy is in the constellation of Ursa Major (also known as the Big Dipper). It is about 70% larger than our own Milky Way Galaxy, with a diameter of about 170,000 light years, and sits at a distance of 21 million light years from Earth. This means that the light were seeing in this image left the Pinwheel Galaxy about 21 million years ago - many millions of years before humans ever walked the Earth. The red colors in the image show infrared light, as seen by the Spitzer Space Telescope. These areas show the heat emitted by dusty lanes in the galaxy, where stars are forming. The yellow component is visible light, observed by the Hubble Space Telescope. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes seen in the infrared. The blue areas are ultraviolet light, given out by hot, young stars that formed about 1 million years ago. The Galaxy Evolution Explorer (GALEX) captured this component of the image. Finally, the hottest areas are shown in purple, where the Chandra X-ray observatory observed the X-ray emission from exploded stars, million-degree gas, and material colliding around black holes.

This graphic illuminates the process by which astronomers using NASA's Spitzer Space Telescope have for the first time detected the light from a super Earth planet. The planet 55 Cancri e orbits very closely to its star, and no current telescope can make an image of it separate from its star. Instead astronomers watch the combined light of the system over time, looking for slight drops in the total light that hint at the existence of planets. Planets like 55 Cancri e are first identified when they "transit," or pass in front of, their star. This blocks a portion of the star's light that is proportional to the size of the planet. Detecting the light from the planet is much harder. When the planet passes behind its star (an "occultation"), there is a slight dip in the total light that corresponds to the light from the planet itself. In visible light this dip is expected to be tiny, only a few parts per million. In infrared light the thermal glow of the planet is much brighter, making the occultation easier to detect. This infrared occultation has been detected by Spitzer, giving astronomers the first-ever measurement of the light from such a small planet (about twice the size of the Earth). Such measurements help astronomers determine conditions on the planet itself.

Super Earths are exotic planets unlike any in our solar system. They are more massive than Earth yet lighter than gas giants like Neptune, and they can be made of gas, rock or a combination of both. There are about 70 known to circle stars beyond our sun, and NASA's Kepler mission has detected hundreds of candidates. These planets' relatively small sizes make them very hard to see. NASA's Spitzer Space Telescope was able to detect a super Earth's direct light for the first time using its sensitive heat-seeking infrared vision. Seen here in this artist's concept, the planet is called 55 Cancri e. It's a toasty world that rushes around its star every 18 hours. It orbits so closely -- about 25 times closer than Mercury is to our sun -- that it is tidally locked with one face forever blisters under the heat of its sun. The planet is proposed to have a rocky core surrounded by a layer of water in a "supercritical" state, where it is both liquid and gas, and then the whole planet is thought to be topped by a blanket of steam. Spitzer was able to see the light of the planet by watching it slip behind its star in what is called an occultation. Because the planet is brighter relative to its star when viewed in infrared light, Spitzer was able to measure the slight drop in total brightness that occurred as the planet disappeared from view. This technique, pioneered by Spitzer in 2005, has since been performed by other telescopes, including NASA's Hubble and Kepler space telescopes. The method can be used to obtain information about a planet's temperature, and in some cases, its composition. In this current study, the Spitzer data revealed that 55 Cancri e is very dark and that its sun-facing side is blistering hot at 2,000 kelvins or 3,140 degrees Fahrenheit.

NASA's Spitzer Space Telescope was able to detect a super Earth's direct light for the first time using its sensitive heat-seeking infrared vision. Super Earths are more massive than Earth but lighter than gas giants like Neptune. As this artist's concept shows, in visible light, a planet is lost in the glare of its star (top view). When viewed in infrared, the planet becomes brighter relative to its star. This is largely due to the fact that the planet's scorching heat blazes with infrared light. Even on our own bodies emanate more infrared light than visible due to our heat. Spitzer cannot distinguish between the planet and star -- it just sees the total light of the system. However, its infrared eyes can see the dip in total light that occurs as a planet passes behind its star (the dip is minuscule when viewed in visible light). The resulting drop then reveals how much direct light comes from the planet itself. This information can be used to determine a planet's temperature, and in some cases, composition. For 55 Cancri e, the Spitzer observations indicated that the planet is very dark and that its sun-facing side is scorching hot, about 2,000 kelvins (3,140 degrees Fahrenheit).

This plot of data from NASA's Spitzer Space Telescope reveals the light from a "super Earth" called 55 Cancri e. The planet is the smallest yet, beyond our solar system, to reveal its direct light. Super Earths are more massive than Earth but lighter than gas giants like Neptune. While this planet is not habitable, the observations are an important milestone toward being able to eventually perform a similar technique on even smaller, potentially Earth-like planets. The plot shows how the infrared light from the 55 Cancri system, both the star and planet, changed as the planet passed behind its star in what is called an occultation. When the planet disappeared, the total light dropped, and then increased back to normal levels as the planet circled back into view. The drop indicated how much light came directly from the planet itself. This type of information is important for studying the temperatures and compositions of planetary atmospheres beyond our own.

'The infrared vision of NASA's Spitzer Space Telescope has revealed that the Sombrero galaxy -- named after its appearance in visible light to a wide-brimmed hat -- is in fact two galaxies in one. It is a large elliptical galaxy (blue-green) with a thin disk galaxy (partly seen in red) embedded within. Previous visible-light images led astronomers to believe the Sombrero was simply a regular flat disk galaxy. Spitzer's infrared view highlights the stars and dust. The starlight detected at 3.5 and 4.6 microns is represented in blue-green while the dust detected at 8.0 microns appears red. This image allowed astronomers to sample the full population of stars in the galaxy, in addition to its structure. The flat disk within the galaxy is made up of two portions. The inner disk is composed almost entirely of stars, with no dust. Beyond this is a slight gap, then an outer ring of intermingled dust and stars, seen here in red.

New observations from NASA's Spitzer Space Telescope reveal the Sombrero galaxy is not simply a regular flat disk galaxy of stars as previously believed, but a more round elliptical galaxy with a flat disk tucked inside. Spitzer's infrared vision allowed astronomers to sample the entire population of the galaxy's stars, as seen in this view in which starlight appears blue-green. The elliptical galaxy is so large that is spills beyond the edges of Spitzer's view. Within the elliptical is a flat disk galaxy. The disk itself shows hints of an inner, bright disk separated by a slight gap from an outer ring. The disk galaxy falls well within the bounds of the outer elliptical. In previous images taken by visible telescopes, the galaxy's flat disk is the most prominent feature. The overall appearance resembles a wide-brimmed hat, or sombrero, hence the galaxy's name. Visible-light views missed the elliptical, or more round, nature of the galaxy, because the old stars dominating the elliptical structure are very dim when viewed at visible-light wavelengths. These same stars stood out when viewed in infrared light by Spitzer, allowing astronomers to re-classify the galaxy as an elliptical with a disk inside. Infrared light of 3.5 and 4.6 microns is color-coded blue-green in this view.

This composite of 30 Doradus, aka the Tarantula Nebula, contains data from Chandra (blue), Hubble (green), and Spitzer (red). Located in the Large Magellanic Cloud, the Tarantula Nebula is one of the largest star-forming regions close to the Milky Way. Chandra's X-rays detect gas that has been heated to millions of degrees by stellar winds and supernovas. This high-energy stellar activity creates shock fronts, which are similar to sonic booms. Hubble reveals the light from massive stars at various stages of star birth, while Spitzer shows where the relatively cooler gas and dust lie.

A huge team of volunteers from the general public has poured over observations from NASA's Spitzer Space Telescope and discovered more than 5,000 "bubbles" in the disk of our Milky Way galaxy. Young, hot stars blow these shells out into surrounding gas and dust, highlighting areas of brand new star formation. Upwards of 35,000 "citizen scientists" sifted through the Spitzer infrared data as part of the online Milky Way Project to find these telltale bubbles. The users have turned up 10 times as many bubbles as previous surveys so far. Volunteers for the project are shown a small section of Spitzers huge infrared Milky Way image (left) that they then scan for cosmic bubbles. Using a sophisticated drawing tool, the volunteers trace the shape and thickness of the bubbles. All of the user drawings can be overlaid on top of one another to form a so-called heat map (middle). Features that have been identified repeatedly by many different users jump out, revealing the overall pattern of bubbles in this part of the galaxy. At least five volunteers must flag a candidate bubble before it is included in the final catalog (right). The brightness of each bubble in the catalog is determined by its hit rate, or the fraction of users who traced it out. The faintest ones were identified by 10% of the users, while solid white indicates a hit rate of 50% or better. After identifying all apparent bubbles, which can include wispy arcs of partially broken rings and the circles-within-circles of overlapping bubbles, volunteers get another of the 12,263 possible image sections to scrutinize. With so much sky to cover, it is clear why so many volunteers are needed to do this kind of science!

If astronomy had its own Academy Awards, then this part of the Milky Way would have been the Favorite Nebula pick for 2011. Competing against 12,263 other slices of the sky, this got more votes from the 35,000 volunteers searching for cosmic bubbles than any other location. The volunteers are all citizen scientists working on the Milky Way Project, scanning a vast collection of infrared images from NASAs Spitzer Space Telescope. Their goal is to identify bubbles that have been blown into gas and dust by stars forming in our Milky Way galaxy. The volunteers study image after image, drawing circles around possible bubbles. Together their efforts have produced a catalog of more than 5,000 bubbles, 10 times what was known before. While scrutinizing each of the images, the volunteers can to bookmark favorite areas. The bright yellow-red nebula at the center of this image garnered the most votes.Interestingly this nebula, which is in the constellation of Scutum, has no common name since it is hidden behind dust clouds. It takes an infrared telescope like Spitzer, which sees beyond the visible spectrum of light, to see through this dark veil and reveal this spectacular hidden nebula. We are seeing stars in the process of forming within this audience-favorite nebula, as well in the surrounding areas in this image.