Messier 74, also known as the Phantom Galaxy, is seen here in infrared light which showcases its sweeping spiral arms and star-forming regions. This image was created using archival data from NASA's Spitzer Space Telescope, revealing dust clouds that, in visible light, appear dark. Messier 74 is an archetype of the "grand design" spiral galaxy and is nearly face-on to our view, providing a perfect view of its structure. In this infrared image, the light from stars appears blue, as stars are brightest at shorter wavelengths of infrared light and less visible at longer wavelengths. The dust clouds, which light up at longer wavelengths of light, are rendered as red. Filamentary dust clouds are a feature of spiral arms, and help to trace regions where gas reaches higher densities and can lead to the formation of stars. The galaxy is located in the Pisces constellation and is situated about 30 million light-years away. It has a visible diameter of approximately 10 arc minutes, which is about a third as wide as the full moon. However, its low surface brightness makes it too faint to be seen with the naked eye and makes it a challenging target even for small backyard telescopes. In this image, infrared light at wavelengths of 3.6, 4.5, and 8.0 microns is displayed as blue, green, and red, respectively.

Messier 74, also known as the Phantom Galaxy, is seen here in infrared light which showcases its sweeping spiral arms and star-forming regions. This image was created using archival data from NASA's Spitzer Space Telescope, revealing dust clouds that, in visible light, appear dark. Messier 74 is an archetype of the "grand design" spiral galaxy and is nearly face-on to our view, providing a perfect view of its structure. In this infrared image, the light from stars appears blue, as stars are brightest at shorter wavelengths of infrared light and less visible at longer wavelengths. Filamentary dust clouds are a feature of spiral arms, and help to trace regions where gas reaches higher densities and can lead to the formation of stars. These clouds light up at longer wavelengths of light, appearing as pale yellow filaments. Regions of newly-forming stars show up as bright red dots scattered along the arms, as they glow most brightly at the longest infrared wavelengths in this image. The galaxy is located in the Pisces constellation and is situated about 30 million light-years away. It has a visible diameter of approximately 10 arc minutes, which is about a third as wide as the full moon. However, its low surface brightness makes it too faint to be seen with the naked eye and makes it a challenging target even for small backyard telescopes. In this image, infrared light at wavelengths of 3.6, 4.5, and 8.0 microns from Spitzer’s IRAC instrument is displayed as blue, cyan, and green, respectively, while light from Spitzer’s MIPS instrument at 24 microns is shown in red.

This new image of the Orion Nebula produced using previously released data from three telescopes shows two enormous caverns carved out by unseen giant stars that can release up to a million times more light than our Sun. All that radiation breaks apart dust grains there, helping to create the pair of cavities. Much of the remaining dust is swept away when the stars produce wind or when they die explosive deaths as supernovae. This infrared image shows dust but no stars. Blue light indicates warm dust heated by unseen massive stars. Observed in infrared light – a range of wavelengths outside what human eyes can detect – the views were provided by NASA’s retired Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (WISE), which now operates under the moniker NEOWISE. Spitzer and WISE were both managed by NASA’s Jet Propulsion Laboratory in Southern California, which is a division of Caltech. Around the edge of the two cavernous regions, the dust that appears green is slightly cooler. Red indicates cold dust that reaches temperatures of about minus 440 Fahrenheit (minus 260 Celsius). The cold dust appears mostly on the outskirts of the dust cloud, away from the regions where stars form. The red and green light shows data from the now-retired Herschel Space Telescope, an ESA (European Space Agency) observatory that captured wavelengths in the far-infrared and microwave ranges, where cold dust radiates. In between the two hollow regions are orange filaments where dust condenses and forms new stars. Over time, these filaments may produce new giant stars that will once again reshape the region.

These graphs show how the light from brown dwarfs are seen to vary over time. The infrared brightnesses were measured by NASA’s Spitzer Space Telescope and demonstrate a wide range of variability in a large number of young brown dwarfs, indicative of their rotation and weather patterns. Blue points represent the individual measurements while the pink line shows a calculated brightness curve fit to the data. These represent a selection of objects studied by Johanna Vos and her team which were presented at a AAS press conference on January 13th, 2022.

Do you see a monster in this picture? Do the bright spots near the top of the image look like the piercing eyes and elongated snout of Godzilla? In reality, this colorful image shows a nebula – a cloud of gas and dust in space – captured by NASA’s Spitzer Space Telescope. Over billions of years, countless stars have formed in the material there. During their lifetimes, the radiation they release carves away the gas and dust, reshaping the cloud. Major changes also occur when massive stars die and explode, becoming supernovae. When viewed in visible light, the kind human eyes can detect, this region is almost entirely obscured by dust clouds. But infrared light (wavelengths longer than what our eyes can perceive) can penetrate the clouds, revealing hidden regions like this one. Three colors (blue, green, and red) are used to represent different wavelengths of infrared light; yellow and white are combinations of those wavelengths. Blue represents wavelengths primarily emitted by stars; dust and organic molecules called hydrocarbons appear green; and warm dust that’s been heated by stars or supernovae appears red. The Godzilla-like nebula is located is in the constellation Sagittarius, along the plane of the Milky Way, which was part of Spitzer’s GLIMPSE Survey (short for Galactic Legacy Infrared Mid-Plane Survey Extraordinaire). Stars in the upper right (where this cosmic Godzilla’s eyes and snout would be) are an unknown distance from Earth but within our galaxy. Located about 7,800 light-years from Earth, the bright region in the lower left (Godzilla’s right hand) is known as W33.

Can you see the dark spot moving in the bottom left corner of the screen? It’s a brown dwarf nicknamed “The Accident,” which was discovered by citizen scientist Dan Caselden. It had slipped past typical searches because it doesn’t look like any other known brown dwarfs.

A contingent of young stars and star-forming gas clouds is sticking out of one of the Milky Way's spiral arms like a splinter protruding from a plank of wood. Stretching some 3,000 light-years, this is the first major structure identified with such a dramatically different orientation relative to the arm. This diagram shows the structure, as well as its size and distance from the Sun. The nearby spiral arms are also noted. The star shapes indicate a star-forming region that may contain anywhere from dozens to thousands of stars. (Among these are the Eagle Nebula, the Omega Nebula, the Trifid Nebula, and the Lagoon Nebula). These stars and star-forming regions are moving through space together, at roughly the same speed and in the same direction. A key property of spiral arms is how tightly they wind around a galaxy. This characteristic is measured by the arm's pitch angle. A circle has a pitch angle of 0 degrees; as the spiral becomes more open, the pitch angle increases. Most models of the Milky Way suggest that the Sagittarius Arm forms a spiral that has a pitch angle of about 12 degrees, but the protruding structure has a pitch angle of nearly 60 degrees. Similar structures – sometimes called spurs or feathers – are commonly found jutting out of the arms of other spiral galaxies. For decades scientists have wondered whether our Milky Way's spiral arms are also dotted with these structures or if they are relatively smooth.

These four nebulae (star-forming clouds of gas and dust) are known for their breathtaking beauty: the Eagle Nebula (which contains the Pillars of Creation), the Omega Nebula, the Trifid Nebula, and the Lagoon Nebula. In the 1950s, a team of astronomers made rough distance measurements to some of the stars in these nebulae and were able to infer the existence of the Sagittarius Arm. Their work provided some of the first evidence of our galaxy's spiral structure. In a new study, astronomers have shown that these nebulae are part of a substructure within the arm that is angled differently from the rest of the arm. A key property of spiral arms is how tightly they wind around a galaxy. This characteristic is measured by the arm's pitch angle. A circle has a pitch angle of 0 degrees, and as the spiral becomes more open, the pitch angle increases. Most models of the Milky Way suggest that the Sagittarius Arm forms a spiral that has a pitch angle of about 12 degrees, but the protruding structure has a pitch angle of nearly 60 degrees. Similar structures – sometimes called spurs or feathers – are commonly found jutting out of the arms of other spiral galaxies. For decades scientists have wondered whether our Milky Way's spiral arms are also dotted with these structures or if they are relatively smooth.

A contingent of young stars and star-forming gas clouds is sticking out of one of the Milky Way's spiral arms like a splinter protruding from a plank of wood. Stretching some 3,000 light-years, this is the first major structure identified with such a dramatically different orientation relative to the arm. The background image shows the location of the splinter in the Milky Way. The yellow region in the center of the image is the galaxy's bright and crowded center. The galaxy's arms spiral around the center, and are full of stars and star-forming clouds of gas and dust. The inset (Figure 1) provides a closer view of the structure, as well as its size and distance from the Sun. The nearby spiral arms are also noted. The star shapes indicate a star-forming region that may contain anywhere from dozens to thousands of stars. (Among these are the Eagle Nebula, the Omega Nebula, the Trifid Nebula, and the Lagoon Nebula). These stars and star-forming regions are moving through space together, at roughly the same speed and in the same direction. A key property of spiral arms is how tightly they wind around a galaxy. This characteristic is measured by the arm's pitch angle. A circle has a pitch angle of 0 degrees; as the spiral becomes more open, the pitch angle increases. Most models of the Milky Way suggest that the Sagittarius Arm forms a spiral that has a pitch angle of about 12 degrees, but the protruding structure has a pitch angle of nearly 60 degrees. Similar structures – sometimes called spurs or feathers – are commonly found jutting out of the arms of other spiral galaxies. For decades scientists have wondered whether our Milky Way's spiral arms are also dotted with these structures or if they are relatively smooth.

This image shows galaxy Arp 148, captured by NASA's Spitzer and Hubble telescopes. Also known as "Mayall's Object," Arp 148 captures a point in the interaction of two galaxies in which a ring has formed in the wake of their collision. The thick clouds of dusty material in the elongated galaxy (left) glow brightly in the infrared wavelengths of light seen by Spitzer (8 microns, red), while the glow of starlight dominates the visible light data from Hubble (0.3-0.8 microns, blue-green).

This image shows galaxy Arp 148, captured by NASA's Spitzer and Hubble telescopes. Inside the white circle is specially-processed Spitzer data, which reveals infrared light from a supernova that is hidden by dust. Supernovae are massive stars that have exploded after running out of fuel. They radiate most brightly in visible light (the kind the human eye can detect), but these wavelengths are obscured by dust. Infrared light, however, can pass through dust. The analysis of Arp 148 was part of an effort to find hidden supernovae in 40 dust-choked galaxies that also emit high levels of infrared light. These galaxies are known as luminous and ultra-luminous infrared galaxies (LIRGs and ULIRGs, respectively). The dust in LIRGs and ULIRGs absorbs optical light from objects like supernovae but allows infrared light from these same objects to pass through unobstructed for telescopes like Spitzer to detect. NASA's Jet Propulsion Laboratory, Pasadena, Calif., 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, also in Pasadena. Caltech manages JPL for NASA. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.

Artist's rendering of a "hot Jupiter," with samples of "light curve" data from hot Jupiters obtained by the Spitzer Space Telescope. Image credit: NASA/JPL-Caltech HIP 67522 b was identified as a planet candidate by NASA's Transiting Exoplanet Survey Satllite (TESS), which detects planets via the transit method: Scientists look for small dips in the brightness of a star, indicating that an orbiting planet has passed between the observer and the star. But young stars tend to have a lot of dark splotches on their surfaces - starspots, also called sunspots when they appear on the Sun - that can look similar to transiting planets. So scientists used data from NASA's recently retired infrared observatory, the Spitzer Space Telescope, to confirm that the transit signal was from a planet and not a starspot. (Other methods of exoplanet detection have yielded hints at the presence of even younger hot Jupiters, but none have been confirmed.)

The Spitzer Space Telescope, launched in 2003, on a mission to become NASA’s premier infrared light observatory. It offered astronomers an unprecedented infrared view of the universe, allowing us to peer into regions of space that are hidden from optical telescopes with unprecedented clarity and sensitivity. One of NASA’s Great Observatories, Spitzer discovered a ring of Saturn, studied some of the farthest galaxies, and identified two of the most distant supermassive black holes ever discovered, among other accomplishments in its 16 years of operation. The study of exoplanets – planets outside our solar system – was not one of Spitzer’s original goals. But innovations during its mission improved Spitzer's precision and enabled it to become a critical tool for exoplanet work. Spitzer marked a new age in planetary science by being the first telescope to directly detect light from exoplanets. It has played a key scientific role in everything from planets larger than Jupiter to small, rocky worlds that may be similar to Earth. In 2017, Spitzer helped reveal TRAPPIST-1, the first known system of seven Earth-sized planets. The discovery set a new record for the greatest number of habitable-zone planets found around a single star outside our solar system. Data from Spitzer also showed that all of these planets are likely to be rocky. Studying TRAPPIST-1 leads scientists a step closer to answering the question "Are we alone?" This poster depicts the TRAPPIST-1 planets, some of which were discovered by Spitzer. The physical characteristics of the planets are not currently known, beyond their mass and distance from the TRAPPIST-1 star, which is visualized in the background. The James Webb Space Telescope is expected to teach us more about this fascinating system.

This illustration depicts the fastest spinning brown dwarf found to date. Astronomers using NASA's Spitzer Space Telescope found 2MASS J0348-6022 rotates on its axis every 1.08 hours, about ten times faster than Jupiter and Saturn. The faster a brown dwarf spins, the narrower the different-colored atmospheric bands on it likely become, as shown in this illustration. Some brown dwarfs glow in visible light, but they are typically brightest in infrared wavelengths, which are longer than what human eyes can see. Brown dwarfs are more massive than most planets but not quite as massive as stars. Generally speaking, they have between 13 and 80 times the mass of Jupiter. A brown dwarf becomes a star if its core pressure gets high enough to start nuclear fusion.

This illustration shows three possible interiors of the seven rocky exoplanets in the TRAPPIST-1 system, based on precision measurements of the planet densities. Overall the TRAPPIST-1 worlds have remarkably similar densities, which suggests they may share the same ratio of common planet-forming elements. The planet densities are slightly lower than those of Earth or Venus, which could mean they contain fractionally less iron (a highly dense material) or more low-density materials, such as water or oxygen. In the first model (left), the interior of the planet is composed of rock mixed with iron bound to oxygen. There is no solid iron core, which is the case with Earth and the other rocky planets in our own solar system. The second model shows an overall composition similar to Earths, in which the densest materials have settled to the center of the planet, forming an iron-rich core proportionally smaller than Earths core. A variation is shown in the third panel, where a larger, denser core could be balanced by an extensive low-density ocean on the planet's surface. However, this scenario can be applied only to the outer four planets in the TRAPPIST-1 system. On the inner three planets, any oceans would vaporize due to the higher temperatures near their star, and a different composition model is required. Since all seven planets have remarkably similar densities, it is more likely that all the planets share a similar bulk composition, making this fourth scenario unlikely but not impossible. The high-precision mass and diameter measurements of the exoplanets in the TRAPPIST-1 system have allowed astronomers to calculate the overall densities of these worlds with an unprecedented degree of accuracy in exoplanet research. Density measurements are a critical first step in determining the composition and structure of exoplanets, but they must be interpreted through the lens of scientific models of planetary structure.

Detailed measurements of the physical properties of the seven rocky TRAPPIST-1 planets and the four terrestrial planets in our solar system help scientists find similarities and differences between the two planet families.

Measuring the mass and diameter of a planet reveals its density, which can give scientists clues about its composition. Scientists now know the density of the seven TRAPPIST-1 planets with a higher precision than any other planets in the universe, other than those in our own solar system

This graph presents measured properties of the seven TRAPPIST-1 exoplanets (labeled b through h), showing how they stack up with one another as well as with Earth and the other inner rocky worlds in our own solar system. The relative sizes of the planets are indicated by the circles. All of the known TRAPPIST-1 planets are larger than Mars, with five of them within 15% of the diameter of Earth. The vertical axis shows the uncompressed densities of the planets. Density, calculated from a planets mass and volume, is the first important step in understanding its composition. Uncompressed density takes into account that the larger a planet is, the more its own gravity will pack the planets material together and increase its density. Uncompressed density, therefore, usually provides a better means of comparing the composition of planets. The plot shows that the uncompressed densities of the TRAPPIST-1 planets are similar to one another, suggesting they may have all have a similar composition. The four rocky planets in our own solar system show more variation in density compared to the seven TRAPPIST-1 planets. Mercury, for example, contains a much higher percentage of iron than the other three rocky planets and thus has a much higher uncompressed density. The horizontal axis shows the level of illumination that each planet receives from its host star. The TRAPPIST-1 star is a mere 9% the mass of our Sun, and its temperature is much cooler. But because the TRAPPIST-1 planets orbit so closely to their star, they receive comparable levels of light and heat to Earth and its neighboring planets. The corresponding habitable zones regions where an Earth-like planet could potentially support liquid water on its surface of the two planetary systems are indicated near the top of the plot. The the two zones do not line up exactly because the cooler TRAPPIST-1 star emitting more of its light in the form of infrared radiation that is more efficiently absorbed by an Earth-like atmosphere. Since it takes less illumination to reach the same temperatures, the habitable zone shifts farther away from the star. The masses and densities of the TRAPPIST-1 planets were determined by measurements of slight variations in the timings of their orbits using extensive observations made by NASAs Spitzer and Kepler space telescopes, in combination with data from Hubble and a number of ground-based telescopes. The latest analysis, which includes Spitzers complete record of over 1,000 hours of TRAPPIST-1 observations, has reduced the uncertainties of the mass measurements to a mere 3-6%. These are among the most accurate measurements of planetary masses anywhere outside of our solar system.

Do you ever look up at the night sky and feel like someone, or something, may be looking back at you? This Halloween image from NASAs Spitzer Space Telescope may convince you that you are right. Dont expect to see these cosmic eyes without a face if you search the night sky with your own binoculars or telescopethey are completely cloaked from view in visible light. They can only be found by telescopes, like Spitzer, that can see infrared light. Lurking in the constellation of Aquila (Latin for eagle), these celestial eyeballs are actually vast bubbles of dust and gas associated with the formation of new stars. Spitzer found that our Milky Way is full of these dusty bubbles. Contributions from nearly 80,000 citizen scientists have helped catalog 2,600 such objects for the Milky Way Project. The two shown here have the lengthy designations MWP1G043734+001170 and MWP1G043775+000606, or N89 and N90 for short. However, very few of these star-forming bubbles give the creepy impression that they are staring back at you. Learn more about these bubbly stellar nurseries in this NASA/JPL news release: http://www.spitzer.caltech.edu/news/2198-ssc2019-16-Spitzer-Spots-a-Starry-Region-Bursting-With-Bubbles What kind of otherworldly creature do you think would be hiding behind this ghostly gaze? Show the world by drawing your own galactic ghoul using our web tool. Take a screen capture and share your creations on social media using the hashtag #NASAHalloween. http://www.spitzer.caltech.edu/design-a-ghoul

The nebula known as W51 is one of the most active star-forming regions in the Milky Way galaxy. First identified in 1958 by radio telescopes, it makes a rich cosmic tapestry in this image from NASA's recently retired Spitzer Space Telescope. Located about 17,000 light-years from Earth, in the direction of the constellation Aquila in the night sky, W51 is about 350 light-years - or about 2 quadrillion miles - across. It is almost invisible to telescopes that collect visible light (the kind human eyes detect), because that light is blocked by interstellar dust clouds that lie between W51 and Earth. But longer wavelengths of light, including radio and infrared, can pass unencumbered through the dust. When viewed in infrared by Spitzer, W51 is a spectacular sight: Its total infrared emission is the equivalent of 20 million Suns.

This artwork illustrates the newly-discovered the exoplanet HIP 67522 b, which appears to be the youngest hot Jupiter ever found. It orbits a well-studied star that is about 17 million years old, meaning the hot Jupiter is likely only a few million years younger, whereas most known hot Jupiters are more than a billion years old. The planet takes about seven days to orbit its star, which has a mass similar to the Sun's. Located only about 490 light-years from Earth, HIP 67522 b is about 10 times the diameter of Earth, or close to that of Jupiter. Its size strongly indicates that it is a gas-dominated planet. HIP 67522 b was identified as a planet candidate by NASA's Transiting Exoplanet Survey Satllite (TESS), which detects planets via the transit method: Scientists look for small dips in the brightness of a star, indicating that an orbiting planet has passed between the observer and the star. But young stars tend to have a lot of dark splotches on their surfaces - starspots, also called sunspots when they appear on the Sun - that can look similar to transiting planets. So scientists used data from NASA's recently retired infrared observatory, the Spitzer Space Telescope, to confirm that the transit signal was from a planet and not a starspot. (Other methods of exoplanet detection have yielded hints at the presence of even younger hot Jupiters, but none have been confirmed.)

Two supermassive black holes are locked in an orbital dance at the core of the distant galaxy OJ 287. This diagram shows their sizes relative to the solar system. The larger one, with about 18 billion times the mass of our sun (right), would encompass all the planets in the solar system with room to spare. The smaller one is about 150 million times the mass of our sun (left), which would be large enough to swallow up everything out to the asteroid belt, just inside the orbit of Jupiter.

This artwork shows two massive black holes in the OJ 287 galaxy. The smaller black hole orbits the larger one, which remains stationary and is surrounded by a disk of gas. When the smaller black hole crashes through the disk, it produces a flare brighter than 1 trillion stars. But the smaller black hole's orbit is elongated and moving relative to the disk, causing the flares to occur irregularly.

This series of image taken by NASA's Spitzer Space Telescope on Jan. 25, 2020, shows part of the California Nebula, which is located about 1,000 light-years from Earth. This is the final mosaic taken by the mission before it was decommissioned on Jan. 30, 2020. Spitzer's infrared detectors reveal the presence of warm dust, similar to soot, mixed in with the gas. The dust absorbs visible and ultraviolet light from nearby stars and then re-emits the absorbed energy as infrared light. The image displays Spitzer's observations much the way that research astronomers would view them: From 2009 to 2020, Spitzer operated two detectors simultaneously that imaged adjacent areas of the sky. The detectors captured different wavelengths of infrared light (referred to by their physical wavelength): 3.6 micrometers (shown in cyan) and 4.5 micrometers (shown in red). Different wavelengths of light can reveal different objects or features. Spitzer would scan the sky, taking multiple pictures in a grid pattern, so that both detectors would image the region at the center of the grid. By combining those images into a mosaic, it was possible to see what a given region looked like in multiple wavelengths, such as in the gray-hued part of the image above. NASA's Jet Propulsion Laboratory, Pasadena, Calif., 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, also in Pasadena. Caltech manages JPL for NASA.

This image shows the section of the nebula captured by Spitzer in the context of a larger, visible-light image of the nebula. This series of image taken by NASA's Spitzer Space Telescope on Jan. 25, 2020, shows part of the California Nebula, which is located about 1,000 light-years from Earth. This is the final mosaic taken by the mission before it was decommissioned on Jan. 30, 2020. Spitzer's infrared detectors reveal the presence of warm dust, similar to soot, mixed in with the gas. The dust absorbs visible and ultraviolet light from nearby stars and then re-emits the absorbed energy as infrared light. NASA's Jet Propulsion Laboratory, Pasadena, Calif., 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, also in Pasadena. Caltech manages JPL for NASA.

For the first time, scientists have directly measured wind speed on a brown dwarf, pictured here in an illustration. Brown dwarfs are objects larger than Jupiter (the largest planet in our solar system) but not quite massive enough to become stars. To achieve the finding, they used a new method that could also be applied to learn about the atmospheres of gas-dominated planets outside our solar system. Described in a paper in the journal Science, the work combines observations by a group of radio telescopes with data from NASA's recently retired infrared observatory, the Spitzer Space Telescope, managed by the agency's Jet Propulsion Laboratory in Southern California. Officially named 2MASS J10475385+2124234, the target of the new study was located 32 light-years from Earth - a stone's throw away, cosmically speaking. It is one of the coldest known brown dwarfs.. The researchers detected winds moving around the planet at 1,425 mph (2,293 kph). For comparison, Neptune's atmosphere features the fastest winds in the solar system, which whip through at more than 1,200 mph (about 2,000 kph).

Brown dwarfs are more massive than planets but not quite as massive as stars. Generally speaking, they have between 13 and 80 times the mass of Jupiter. A brown dwarf becomes a star if its core pressure gets high enough to start nuclear fusion.

This artist's concept shows planet KELT-9b orbiting its host star, KELT-9. It is the hottest gas giant planet discovered so far. Now, a team of astronomers using NASA's Spitzer space telescope has found evidence that the heat is too much even for molecules to remain intact. Molecules of hydrogen gas are likely ripped apart on the dayside of KELT-9b, unable to re-form until their disjointed atoms flow around to the planet's nightside. With a dayside temperature of more than 7,800 degrees Fahrenheit (4,600 Kelvin), KELT-9b is a planet that is hotter than most stars. But its star, called KELT-9, is even hotter -- a blue A-type star that is likely unraveling the planet through evaporation. KELT-9b is a gas giant 2.8 times more massive than Jupiter, but only half as dense. Scientists would expect the planet to have a smaller radius, but the extreme radiation from its host star has caused the planet's atmosphere to puff up like a balloon. The planet is also unusual in that it orbits perpendicular to the spin axis of the star. That would be analogous to the planet orbiting perpendicular to the plane of our solar system. One "year" on this planet is less than two days long. The KELT-9 star is only 300 million years old, which is young in star time. It is more than twice as large, and nearly twice as hot, as our sun. Given that the planet's atmosphere is constantly blasted with high levels of ultraviolet radiation, the planet may even be shedding a tail of evaporated planetary material like a comet.

This artist's concept shows planet KELT-9b orbiting its host star, KELT-9. It is the hottest gas giant planet discovered so far. Now, a team of astronomers using NASA's Spitzer space telescope has found evidence that the heat is too much even for molecules to remain intact. Molecules of hydrogen gas are likely ripped apart on the dayside of KELT-9b, unable to re-form until their disjointed atoms flow around to the planet's nightside. With a dayside temperature of more than 7,800 degrees Fahrenheit (4,600 Kelvin), KELT-9b is a planet that is hotter than most stars. But its star, called KELT-9, is even hotter -- a blue A-type star that is likely unraveling the planet through evaporation. KELT-9b is a gas giant 2.8 times more massive than Jupiter, but only half as dense. Scientists would expect the planet to have a smaller radius, but the extreme radiation from its host star has caused the planet's atmosphere to puff up like a balloon. The planet is also unusual in that it orbits perpendicular to the spin axis of the star. That would be analogous to the planet orbiting perpendicular to the plane of our solar system. One "year" on this planet is less than two days long. The KELT-9 star is only 300 million years old, which is young in star time. It is more than twice as large, and nearly twice as hot, as our sun. Given that the planet's atmosphere is constantly blasted with high levels of ultraviolet radiation, the planet may even be shedding a tail of evaporated planetary material like a comet.