In the summer of the year 1054 AD, Chinese astronomers saw a new "guest star," that appeared six times brighter than Venus. So bright in fact, it could be seen during the daytime for several months. This "guest star" was forgotten about until 700 years later with the advent of telescopes. Astronomers saw a tentacle-like nebula in the place of the vanished star and called it the Crab Nebula. Today we know it as the expanding gaseous remnant from a star that self-detonated as a supernova, briefly shining as brightly as 400 million suns. The explosion took place 6,500 light-years away. If the blast had instead happened 50 light-years away it would have irradiated Earth, wiping out most life forms. In the late 1960s astronomers discovered the crushed heart of the doomed star, an ultra-dense neutron star that is a dynamo of intense magnetic field and radiation energizing the nebula. Astronomers therefore need to study the Crab Nebula across a broad range of electromagnetic radiation, from X-rays to radio waves. This image combines data from five different telescopes: the VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple. The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington, D.C. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations. NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

This artist's concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets diameters, masses and distances from the host star. The system has been revealed through observations from NASA's Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope. The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it. They are likely all tidally locked, meaning the same face of the planet is always pointed at the star, as the same side of our moon is always pointed at Earth. This creates a perpetual night side and perpetual day side on each planet. TRAPPIST-1b and c receive the most light from the star and would be the warmest. TRAPPIST-1e, f and g all orbit in the habitable zone, the area where liquid water is most likely to be detected. But any of the planets could potentially harbor liquid water, depending on their compositions. In the imagined planets shown here, TRAPPIST-1b is shown as a larger analogue to Jupiters moon Io.TRAPPIST-1d is depicted with a narrow band of water near the terminator, the divide between a hot, dry day and an ice-covered night side. TRAPPIST-1e and TRAPPIST-1f are both shown covered in water, but with progressively larger ice caps on the night side. TRAPPIST-1g is portrayed with an atmosphere like Neptune's, although it is still a rocky world. TRAPPIST-1h, the farthest from the star, would be the coldest. It is portrayed here as an icy world, similar to Jupiter's moon Europa, but the least is known about it. NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at Caltech/IPAC. Caltech manages JPL for NASA.

This data plot shows infrared observations by NASAs Spitzer Space Telescope of a system of seven planets orbiting TRAPPIST-1, an ultracool dwarf star. Over 21 days, Spitzer measured the drop in light as each planet passed in front of the star. Spitzer was able to identify a total of seven rocky worlds, including three in the habitable zone where liquid water might be found. This plot shows the change in light as each planet passes in front of its star. A diagram of the layouts of the orbits is shown on the right. The study established the planets' size, distance from their sun and, for some of them, their approximate mass and density. It also established that some, if not all, these planets are tidally locked, meaning one face of the planet permanently faces their sun. The system has been revealed through observations from NASA's Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope.

This illustration depicts a newly discovered brown dwarf, an object that weighs in somewhere between our solar system's most massive planet (Jupiter) and the least-massive-known star. This brown dwarf, dubbed OGLE-2015-BLG-1319, interests astronomers because it may fall in the "desert" of brown dwarfs. Scientists have found that, for stars roughly the mass of our sun, less than 1 percent have a brown dwarf orbiting within 3 AU (1 AU is the distance between Earth and the sun). This brown dwarf was discovered when it and its star passed between Earth and a much more distant star in our galaxy. This created a microlensing event, where the gravity of the system amplified the light of the background star over the course of several weeks. This microlensing was observed by ground-based telescopes looking for these uncommon events, and was the first to be seen by two space-based telescopes: NASA's Spitzer and Swift missions. The background data plot shows how the stars brightness evolved over time. The ground-based data is shown in grey, Swift with blue diamonds, and Spitzer with red circles.

This illustration depicts a newly discovered brown dwarf, an object that weighs in somewhere between our solar system's most massive planet (Jupiter) and the least-massive-known star. This brown dwarf, dubbed OGLE-2015-BLG-1319, interests astronomers because it may fall in the "desert" of brown dwarfs. Scientists have found that, for stars roughly the mass of our sun, less than 1 percent have a brown dwarf orbiting within 3 AU (1 AU is the distance between Earth and the sun). This brown dwarf was discovered when it and its star passed between Earth and a much more distant star in our galaxy. This created a microlensing event, where the gravity of the system amplified the light of the background star over the course of several weeks. This microlensing was observed by ground-based telescopes looking for these uncommon events, and was the first to be seen by two space-based telescopes: NASA's Spitzer and Swift missions.

For the first time, two space-based telescopes have teamed up with ground-based observatories to observe a microlensing event, a magnification of the light of a distant star due to the gravitational effects of an unseen object in the foreground. In this case, the cause of the microlensing event was a brown dwarf, dubbed OGLE-2015-BLG-1319, orbiting a star. In terms of mass, brown dwarfs fall somewhere between the size of the largest planets and the smallest stars. Curiously, scientists have found that, for stars roughly the mass of our sun, less than 1 percent have a brown dwarf orbiting within 3 AU (1 AU is the distance between Earth and the sun). This newly discovered brown dwarf may fall in that distance range. This microlensing event was observed by ground-based telescopes looking for these uncommon events, and subsequently seen by NASAs Spitzer and Swift space telescopes. As the diagram shows, Spitzer and Swift offer additional vantage points for viewing this chance alignment. While Swift orbits close to Earth, and saw (blue diamonds) essentially the same change in light that the ground-based telescopes measured (grey markers), Spitzers location much farther away from Earth gave it a very different perspective on the event (red circles). In particular, Spitzers vantage point resulted in a time lag in the microlensing event it observed, compared to what was seen by Swift and the ground-based telescope. This offset allowed astronomers to determine the distance to OGLE-2015-BLG-1319 as well as its mass: around 30-65 times that of Jupiter.

This artist's concept illustrates how the brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. The star is pictured with the disk of material that surrounds it. Researchers found that it has dimmed by about 13 percent at short infrared wavelengths from 2004 to 2016. This illustration represents the 2004 data that was collected with NASA's Spitzer Space Telescope. FU Orionis is a few hundred thousand years old. It is possible that when our sun was younger, it also went through a period of intense brightening followed by dimming.

This artist's concept illustrates how the brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. The star is pictured with the disk of material that surrounds it. Researchers found that it has dimmed by about 13 percent at short infrared wavelengths from 2004 (left) to 2016 (right). This illustration represents the 2016 data was collected with the Stratospheric Observatory for Infrared Astronomy (SOFIA). FU Orionis is a few hundred thousand years old. It is possible that when our sun was younger, it also went through a period of intense brightening followed by dimming.

This artist's concept illustrates how the brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. The star is pictured with the disk of material that surrounds it. Researchers found that it has dimmed by about 13 percent at short infrared wavelengths from 2004 (left) to 2016 (right). The 2004 data were collected with NASA's Spitzer Space Telescope, and the 2016 data were collected with the Stratospheric Observatory for Infrared Astronomy (SOFIA). FU Orionis is a few hundred thousand years old. It is possible that when our sun was younger, it also went through a period of intense brightening followed by dimming. These results were presented at the American Astronomical Association meeting in June 2016 in San Diego. NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at Caltech. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA. SOFIA is a joint project of NASA and the German Aerospace Center (DLR). The aircraft is based at NASA Armstrong Flight Research Center's facility in Palmdale, California. NASA's Ames Research Center in Moffett Field, California, manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA) headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart.

The spider part of "The Spider and the Fly" nebulae, IC 417 abounds in star formation, as seen in this infrared image from NASA's Spitzer Space Telescope and the Two Micron All Sky Survey (2MASS). Located in the constellation Auriga, IC 417 lies about 10,000 light-years away. It is in the outer part of the Milky Way, almost exactly in the opposite direction from the galactic center. This region was chosen as the subject of a research project by a group of students, teachers and scientists as part of the NASA/IPAC Teacher Archive Research Program (NITARP) in 2015. A cluster of young stars called "Stock 8" can be seen at center right. The light from this cluster carves out a bowl in the nearby dust clouds, seen here as green fluff. Along the sinuous tail in the center and to the left, groupings of red point sources are also young stars. In this image, infrared wavelengths, which are invisible to the unaided eye, have been assigned visible colors. Light with a wavelength of 1.2 microns, detected by 2MASS, is shown in blue. The Spitzer wavelengths of 3.6 and 4.5 microns are green and red, respectively. Spitzer data used to create this image were obtained during the space telescope's "warm mission" phase, following its depletion of coolant in mid-2009. Due to its design, Spitzer remains cold enough to operate efficiently at two channels of infrared light. It is now in its 12th year of operation since launch. The 2MASS mission was a joint effort between the California Institute of Technology, Pasadena; the University of Massachusetts, Amherst; and NASA's Jet Propulsion Laboratory, Pasadena, California. JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data from 2MASS and Spitzer are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center (IPAC) at Caltech. Caltech manages JPL for NASA.

This artist's concept shows a hypothetical "rejuvenated" planet -- a gas giant that has reclaimed its youthful infrared glow. NASA's Spitzer Space Telescope found tentative evidence for one such planet around a dead star, or white dwarf, called PG 0010+280 (depicted as white dot in illustration). When planets are young, they are warm and toasty due to internal heat left over from their formation. Planets cool over time -- until they are possibly rejuvenated. The theory goes that this Jupiter-like planet, which orbits far from its star, would accumulate some of the material sloughed off by its star as the star was dying. The material would cause the planet to swell in mass. As the material fell onto the planet, it would heat up due to friction and glow with infrared light. The final result would be an old planet, billions of years in age, radiating infrared light as it did in its youth. Spitzer detected an excess infrared light around the white dwarf PG 0010+280. Astronomers aren't sure where the light is coming from, but one possibility is a rejuvenated planet. Future observations may help solve the mystery. A Jupiter-like planet is about ten times the size of a white dwarf. White dwarfs are about the size of Earth, so one white dwarf would easily fit into the Great Red Spot on Jupiter!

Astronomers were surprised to see these data from NASA's Spitzer Space Telescope in January 2013, showing a huge eruption of dust around a star called NGC 2547-ID8. In this plot, infrared brightness is represented on the vertical axis, and time on the horizontal axis. The data at left show infrared light from the dust around the star back in 2012. Between 2012 and 2013, Spitzer had to stop observing the star because it was located behind the sun, as seen from Spitzer's Earth-trailing orbit. When Spitzer began watching the star again in January 2013, the astronomers noticed a huge jump in the data. (The red and blue data plots show different infrared wavelengths.) Why the dramatic change? The team says that dust in the star system surged intensely, likely after two large asteroids collided, kicking up fresh dust. The periodic variability of the signal is caused by the remaining dust cloud in orbit around the star. This dust cloud is elongated, so the amount of infrared signal it produces changes as it circles the star from our point of view. The infrared signal is decreasing over time as dust from the collision is ground down to finer sizes and blown of the system.

Planets, including those like our own Earth, form from epic collisions between asteroids and even bigger bodies, called proto-planets. Sometimes the colliding bodies are ground to dust, and sometimes they stick together to ultimately form larger, mature planets. This artist's conception shows one such smash-up, the evidence for which was collected by NASA's Spitzer Space Telescope. Spitzer's infrared vision detected a huge eruption around the star NGC 2547-ID8 between August 2012 and 2013. Scientists think the dust was kicked up by a massive collision between two large asteroids. They say the smashup took place in the star's "terrestrial zone," the region around stars where rocky planets like Earth take shape. NGC 2547-ID8 is a sun-like star located about 1,200 light-years from Earth in the constellation Vela. It is about 35 million years old, the same age our young sun was when its rocky planets were finally assembled via massive collisions -- including the giant impact on proto-Earth that led to the formation of the moon. The recent impact witnessed by Spitzer may be a sign of similar terrestrial planet building. Near-real-time studies like these help astronomers understand how the chaotic process works.

This infrared image from NASA's Spitzer Space Telescope shows N103B -- all that remains from a supernova that exploded a millennium ago in the Large Magellanic Cloud, a satellite galaxy 160,000 light-years away from our own Milky Way. Spitzer's instruments pick up infrared light emitted by dust in both the remnant and the surrounding interstellar medium. The infrared light has been translated to colors we see in this image, allowing astronomers to dissect the scene. In this image, dust associated with the remnant appears red, while dust in the ambient background of the galaxy appears yellow and green. Stars in the field appear blue. By studying the infrared light emitted from this supernova remnant, astronomers have determined that the density of the gas surrounding the supernova is much higher than is typical for a 'Type Ia' supernova, which are those that occur when dead stars called white dwarfs explode. Astronomers believe that this dense material was expelled prior to the supernova explosion, possibly by a companion to the white dwarf -- an aging star that shed the material. Most Type Ia supernovas do not show evidence for this process occurring, making N103B an example of a rare subclass of Type Ia explosions. In fact, only one other remnant of a Type Ia explosion shows evidence for this: the remnant of Kepler's supernova in our own galaxy, the remains of the explosion of a star witnessed on Earth in 1604 A.D. The clump of blue stars seen at the lower right is the cluster known as NGC 1850. Also a resident of the Large Magellanic Cloud, this cluster is made up of young stars yet has the appearance of globular clusters in the Milky Way, which are much older. The red data shows infrared light with wavelengths of 16 and 24 microns, while shorter-wavelength infrared light of 3.6, 4.5, and 8 microns is shown as blue, cyan and green, respectively.

Within the swaddling dust of the Serpens Cloud Core, astronomers are studying one of the youngest collections of stars ever seen in our galaxy. This infrared image combines data from NASAs Spitzer Space Telescope with shorter-wavelength observations from the Two Micron All Sky Survey (2MASS), letting us peer into the clouds of dust wrapped around this stellar nursery. At a distance of around 750 light-years, these young stars reside within the confines of the constellation Serpens, or the Serpent. This collection contains stars of only relatively low to moderate mass, lacking any of the massive and incredibly bright stars found in larger star-forming regions like the Orion nebula. Our sun is a star of moderate mass. Whether it formed in a low-mass stellar region like Serpens, or a high-mass stellar region like Orion, is an ongoing mystery. The stellar hatchlings in the Serpens Cloud Core represent the very youngest stages of stellar development. They appear as red, orange and yellow points clustered near the center of the image. Other red features include jets of material ejected from these young stars. Some mature stars that are not in the nebula appear yellowish due to dust obscuring our view at shorter, bluer wavelengths. This region also includes a population of prenatal stars that are so deeply enshrouded in their dusty cocoons to be completely hidden in this view. They only become detectable at much longer wavelengths of light. The inner Serpens Cloud Core is remarkably detailed in this image, as it was assembled from 82 separate snapshots totaling a whopping 16.2 hours of Spitzer observing time. Serpens is one of several star-forming regions targeted by the Young Stellar Object Variability (YSOVAR) project, which conducted repeated observations in each area to look for changes in brightness in the baby stars. Such fluctuations can provide valuable clues to how stars gobble up gas and dust as they grow and mature. Spitzer observations at wavelengths of 3.5 and 4.6 microns are shown in green and red, respectively. 2MASS data at 1.3 microns is displayed as blue. These observations date from Spitzers warm mission phase, following the depletion of its liquid coolant in 2009. The 2MASS mission was a joint effort between the California Institute of Technology, Pasadena, Calif., the University of Massachusetts and NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Within the swaddling dust of the Serpens Cloud Core, astronomers are studying one of the youngest collections of stars ever seen in our galaxy. This infrared image uses data from the warm phase of NASAs Spitzer Space Telescope, letting us peer into the clouds of dust wrapped around this stellar nursery. At a distance of around 750 light-years, these young stars reside within the confines of the constellation Serpens, or the Serpent. This collection contains stars of only relatively low to moderate mass, lacking any of the massive and incredibly bright stars found in larger star-forming regions like the Orion nebula. Our sun is a star of moderate mass. Whether it formed in a low-mass stellar region like Serpens, or a high-mass stellar region like Orion, is an ongoing mystery. The stellar hatchlings in the Serpens Cloud Core represent the very youngest stages of stellar development. They appear as red, orange and yellow points clustered near the center of the image. Other red features include jets of material ejected from these young stars. Some mature stars that are not in the nebula appear yellowish due to dust obscuring our view at shorter, bluer wavelengths. This region also includes a population of prenatal stars that are so deeply enshrouded in their dusty cocoons to be completely hidden in this view. They only become detectable at much longer wavelengths of light. The inner Serpens Cloud Core is remarkably detailed in this image, as it was assembled from 82 separate snapshots totaling a whopping 16.2 hours of Spitzer observing time. Serpens is one of several star-forming regions targeted by the Young Stellar Object Variability (YSOVAR) project, which conducted repeated observations in each area to look for changes in brightness in the baby stars. Such fluctuations can provide valuable clues to how stars gobble up gas and dust as they grow and mature. Spitzer observations at wavelengths of 3.5 and 4.6 microns are shown in blue and orange, respectively. These observations date from Spitzers warm mission phase, following the depletion of its liquid coolant in 2009.

This 4-panel image shows the coldest brown dwarf yet seen, and the fourth closest system to our sun. Called WISE J085510.83-071442.5, this dim object was discovered through its rapid motion across the sky. It was first seen in two infrared images taken six months apart in 2010 by NASA's Wide-field Infrared Survey Explorer, or WISE (see yellow triangles). Two additional images of the object were taken with NASA's Spitzer Space Telescope in 2013 and 2014 (green triangles). All four images were used to measure the distance to the object -- 7.2 light-years -- using the parallax effect. The Spitzer data were used to show that the body is as cold as the North Pole (or between minus 54 and 9 degrees Fahrenheit, which is minus 48 to minus 13 degrees Celsius).

This artist's conception shows the object named WISE J085510.83-071442.5, the coldest known brown dwarf. Brown dwarfs are dim star-like bodies that lack the mass to burn nuclear fuel as stars do. WISE J085510.83-071442.5 is as cold as the North Pole (or between minus 54 and 9 degrees Fahrenheit, which is minus 48 to minus 13 degrees Celsius). The color of the brown dwarf in this image is arbitrary; it would have different colors when viewed in different wavelength ranges. This celestial orb is also the fourth closest to our sun, at 7.2 light-years from Earth. In this illustration, the sun is the bright star directly to the right of the brown dwarf. Our sun's closest neighboring system (not pictured) is Alpha Centauri, at 4 light-years from Earth. The slightly shifted star field accurately reflects how the sky around the constellations of Aquila and Delphinus would appear from the vantage point of WISE J085510.83-071442.5 and was rendered using Microsoft's WorldWide Telescope.

This diagram illustrates the locations of the star systems closest to the sun. The year when the distance to each system was determined is listed after the system's name. NASA's Wide-field Infrared Survey Explorer, or WISE, found two of the four closest systems: the binary brown dwarf WISE 1049-5319 and the brown dwarf WISE J085510.83-071442.5. NASA's Spitzer Space Telescope helped pin down the location of the latter object. The closest system to the sun is a trio of stars that consists of Alpha Centauri, a close companion to it and the more distant companion Proxima Centauri.

Magnetic loops carry gas and dust above disks of planet-forming material circling stars, as shown in this artist's conception. These loops give off extra heat, which NASA's Spitzer Space Telescope detects as infrared light. The colors in this illustration show what an alien observer with eyes sensitive to both visible light and infrared wavelengths might see.

The supernova SN 2014J is seen in this image near its peak brightness in the first week of February 2014. It appears as a faint star to the lower right of the central region of its host galaxy M82. The new supernova is of a particular kind known as a Type Ia. This type of supernova results in the complete destruction of a white dwarf star-the small, dense, aged remnant of a typical star like our Sun. Two scenarios are theorized to give rise to Type Ia supernovas: In a binary star system, a white dwarf gravitationally pulls in matter from its companion star, accruing mass until the white dwarf crosses a critical threshold and blows up. Alternatively, two white dwarfs in a binary system spiral inward toward each other and eventually explosively collide. Studying SN 2014J will help with understanding the processes behind Type Ia detonations to further refine theoretical models. In the image, light from Spitzer's infrared channels are colored blue at 3.6 microns and green at 4.5 microns.

The closest supernova of its kind to be observed in the last few decades has sparked a global observing campaign involving legions of instruments on the ground and in space, including NASA's Spitzer Space Telescope. Dust in the supernova's host galaxy M82, also called the "Cigar galaxy," partially obscures observations in optical and high-energy forms of light. The infrared light that Spitzer sees in, however, can pass through this dust, allowing astronomers to peer directly into the heart of the aftermath of the stellar explosion. This image shows Spitzer's view of M82 on three separate dates: May 9, 2005; February 7, 2014; and February 12, 2014. The observations from February 7 reveal the presence of a bright spot -- the supernova -- not present in the prior observations. By February 12, the supernova has started to dim somewhat from its peak brightness in the first week of February. The supernova, dubbed SN 2014J, was first spotted by human observers on January 21, 2014. SN 2014J is glowing very brightly in the infrared light that Spitzer sees. The telescope was able to observe the supernova before and after it reached its peak brightness. Such early observations with an infrared telescope have only been obtained for a few Type Ia supernovas in the past. Researchers are currently using the data to learn more about how these explosions occur. In the image, light from Spitzer's infrared channels are colored blue at 3.6 microns and green at 4.5 microns.

Roguish runaway stars can have a big impact on their surroundings as they plunge through the Milky Way galaxy. Their high-speed encounters shock the galaxy, creating arcs, as seen in this newly released image from NASAs Spitzer Space Telescope. In this case, the speedster star is known as Kappa Cassiopeiae, or HD 2905 to astronomers. It is a massive, hot supergiant. But what really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy. Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzers infrared detectors. Incredibly, this shock is created about 4 light-years ahead of Kappa Cassiopeiae, showing what a sizable impact this star has on its surroundings. (This is about the same distance that we are from Proxima Centauri, the nearest star beyond the sun.) The Kappa Cassiopeiae bow shock shows up as a vividly red color. The faint green features in this image result from carbon molecules, called polycyclic aromatic hydrocarbons, in dust clouds along the line of sight that are illuminated by starlight. Delicate red filaments run through this infrared nebula, crossing the bow shock. Some astronomers have suggested these filaments may be tracing out features of the magnetic field that runs throughout our galaxy. Since magnetic fields are completely invisible themselves, we rely on chance encounters like this to reveal a little of their structure as they interact with the surrounding dust and gas. Kappa Cassiopeiae is visible to the naked eye in the Cassiopeia constellation (but its bow shock only shows up in infrared light.) For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red.

This artist's concept shows what the weather might look like on cool star-like bodies known as brown dwarfs. These giant balls of gas start out life like stars, but lack the mass to sustain nuclear fusion at their cores, and instead, fade and cool with time. New research from NASA's Spitzer Space Telescope suggests that most brown dwarfs are racked with colossal storms akin to Jupiter's famous "Great Red Spot." These storms may be marked by fierce winds, and possibly lightning. The turbulent clouds might also rain down molten iron, hot sand or salts -- materials thought to make up the cloud layers of brown dwarfs.

Combined observations from NASA's Spitzer Space Telescope and the newly completed Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have revealed the throes of stellar birth, as never before, in the well-studied object known as HH 46/47. Herbig-Haro (HH) objects form when jets shot out by newborn stars collide with surrounding material, producing small, bright, nebulous regions. To our eyes, the dynamics within many HH objects are obscured by enveloping gas and dust. But the infrared and submillimeter light seen by Spitzer and ALMA, respectively, pierces the dark cosmic cloud around HH 46/47 to let us in on the action. (Infrared light has longer wavelengths than what we see with our eyes, and submillimeter light has even longer wavelengths.) In this image, the shorter-wavelength light appears blue and longer-wavelength light, red. Blue shows gas energized by the outflowing jets. The green colors trace a combination of hydrogen gas molecules and dust that follows the boundary of the gas cloud cocooning the young star. The reddish-colored areas, created by excited carbon monoxide gas, reveal that the gas in the two lobes blown out by the star's jets is expanding faster than previously thought. This faster expansion has an influence on the overall amount of turbulence in the gaseous cloud that originally spawned the star. In turn, the extra turbulence could have an impact on whether and how other stars might form in this gaseous, dusty, and thus fertile, ground for star-making.

This artist's conception portrays a free-floating brown dwarf, or failed star. A new study using data from NASA's Spitzer Space Telescope shows that several of these objects are warmer than previously thought, with temperatures about 250 to 350 degrees Fahrenheit (125 to 175 degrees Celsius).

The locations of brown dwarfs discovered by NASA's Wide-field Infrared Survey Explorer, or WISE, and mapped by NASA's Spitzer Space Telescope, are shown in this diagram as red circles. The red lines all link back to the location of the sun. The view is from a vantage point about 100 light-years away from the sun, looking back toward the constellation Orion. At this distance, our sun is barely visible as a speck of light. The vastly fainter brown dwarfs would not even be visible in this view.

Massive stars can wreak havoc on their surroundings, as can be seen in this new view of the Carina nebula from NASAs Spitzer Space Telescope. The bright star at the center of the nebula is Eta Carinae, one of the most massive stars in the galaxy. Its blinding glare is sculpting and destroying the surrounding nebula. Eta Carinae is a true giant of a star. It is around 100 times the mass of our sun and is burning its nuclear fuel so quickly that it is at least one million times brighter than the sun. It has brightened and faded over the years, and some astronomers think it could explode as a supernova in the not-too-distant future. Such a tremendous outflow of energy comes at a great cost to the surrounding nebula. The infrared light from the star destroys particles of dust, sculpting cavities and leaving pillars of denser material that point back to the star. Spitzers infrared vision lets us see the dust, shown in red, as well as clouds of hot, glowing gas that appear green. Spitzer released an image of a small part of this nebula in 2005. Subsequent observations greatly expanded our view of the entire region, and the data were combined and reprocessed as part of the extended Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) project. The infrared images were captured with the Spitzer's infrared array camera. The pictures are three-channel composites, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), and 8.0 microns (red).

In this artist's impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to "blink" every 93 days. The dusty hula hoop itself is misaligned from the central star pair, thanks to the disrupting gravitational presence of a third star orbiting at the periphery of the system. The light yellow arcs near the two central stars indicate their movement relative to each other and the disk. It is believed that this disk will go on to spawn planets and the other celestial bodies that make up a solar system. NASA's Spitzer Space Telescope observed this system, called YLW 16A, in the infrared light emitted by the disk's warmed gas and dust.

Dozens of newborn stars sprouting jets from their dusty cocoons have been spotted in images from NASA's Spitzer Space Telescope. In this view showing a portion of sky near Canis Major, infrared data from Spitzer are green and blue, while longer-wavelength infrared light from NASA's Wide-field Infrared Survey Explorer (WISE) are red. The jets appear in green, while young stars are a yellow-orange hue. Some of the jets can be seen as streaks, while others appear as blobs because only portions of the jet can be seen. In some cases, the stars producing jets can't be seen while their jets can. Those stars are so embedded in their dusty cocoon that they are too faint to be seen at Spitzer's wavelengths. This is a lesser-known region of star formation, located near the outer edge of our Milky Way galaxy. Spitzer is showing that even these more sparse regions of the galaxy are aglow with stellar youth. The pink hues are from organic star-forming molecules called polycyclic aromatic hydrocarbons. Stars in the pink regions are a bit older than the rambunctious ones spewing jets, but still relatively young in cosmic terms. In this image, Spitzer's 3.6- and 4.5-micron data are blue and green, respectively, while WISE's 12-micron data are red. The Spitzer data were taken as part of the mission's Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 360, or Glimpse 360 project, which is pointing the Spitzer Space telescope away from the galactic center to complete a full 360-degree scan of the Milky Way plane. WISE all-sky observations are boosting Spitzer's imaging capabilities by providing the longer-wavelength infrared coverage the mission lost when it ran out of coolant, as planned, in 2009.