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We can agree that nebulae are some of the most majestic-looking objects in the universe. But what are they exactly? Nebulae are giant clouds of gas and dust in space. They’re commonly associated with two parts of the life cycle of stars: First, they can be nurseries forming new baby stars. Second, expanding clouds of gas and dust can mark where stars have died.
Not all nebulae are alike, and their different appearances tell us what's happening around them. Since not all nebulae emit light of their own, there are different ways that the clouds of gas and dust reveal themselves. Some nebulae scatter the light of stars hiding in or near them. These are called reflection nebulae and are a bit like seeing a street lamp illuminate the fog around it.
In another type, called emission nebulae, stars heat up the clouds of gas, whose chemicals respond by glowing in different colors. Think of it like a neon sign hanging in a shop window!
Finally there are nebulae with dust so thick that we’re unable to see the visible light from young stars shine through it. These are called dark nebulae.
Our missions help us see nebulae and identify the different elements that oftentimes light them up.
The Hubble Space Telescope is able to observe the cosmos in multiple wavelengths of light, ranging from ultraviolet, visible, and near-infrared. Hubble peered at the iconic Eagle Nebula in visible and infrared light, revealing these grand spires of dust and countless stars within and around them.
The Chandra X-ray Observatory studies the universe in X-ray light! The spacecraft is helping scientists see features within nebulae that might otherwise be hidden by gas and dust when viewed in longer wavelengths like visible and infrared light. In the Crab Nebula, Chandra sees high-energy X-rays from a pulsar (a type of rapidly spinning neutron star, which is the crushed, city-sized core of a star that exploded as a supernova).
The James Webb Space Telescope will primarily observe the infrared universe. With Webb, scientists will peer deep into clouds of dust and gas to study how stars and planetary systems form.
The Spitzer Space Telescope studied the cosmos for over 16 years before retiring in 2020. With the help of its detectors, Spitzer revealed unknown materials hiding in nebulae — like oddly-shaped molecules and soot-like materials, which were found in the California Nebula.
Studying nebulae helps scientists understand the life cycle of stars. Did you know our Sun got its start in a stellar nursery? Over 4.5 billion years ago, some gas and dust in a nebula clumped together due to gravity, and a baby Sun was born. The process to form a baby star itself can take a million years or more!
After billions more years, our Sun will eventually puff into a huge red giant star before leaving behind a beautiful planetary nebula (so-called because astronomers looking through early telescopes thought they resembled planets), along with a small, dense object called a white dwarf that will cool down very slowly. In fact, we don’t think the universe is old enough yet for any white dwarfs to have cooled down completely.
Since the Sun will live so much longer than us, scientists can't observe its whole life cycle directly ... but they can study tons of other stars and nebulae at different phases of their lives and draw conclusions about where our Sun came from and where it's headed. While studying nebulae, we’re seeing the past, present, and future of our Sun and trillions of others like it in the cosmos.
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Science is a shared endeavor. We learn more when we work together. Today, July 18, we’re using three different space telescopes to observe the same star/planet system!
As our Transiting Exoplanet Survey Satellite (TESS) enters its third year of observations, it's taking a new look at a familiar system this month. And today it won't be alone. Astronomers are looking at AU Microscopii, a young fiery nearby star – about 22 million years old – with the TESS, NICER and Swift observatories.
TESS will be looking for more transits – the passage of a planet across a star – of a recently-discovered exoplanet lurking in the dust of AU Microscopii (called AU Mic for short). Astronomers think there may be other worlds in this active system, as well!
Our Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station will also focus on AU Mic today. While NICER is designed to study neutron stars, the collapsed remains of massive stars that exploded as supernovae, it can study other X-ray sources, too. Scientists hope to observe stellar flares by looking at the star with its high-precision X-ray instrument.
Scientists aren't sure where the X-rays are coming from on AU Mic — it could be from a stellar corona or magnetic hot spots. If it's from hot spots, NICER might not see the planet transit, unless it happens to pass over one of those spots, then it could see a big dip!
A different team of astronomers will use our Neil Gehrels Swift Observatory to peer at AU Mic in X-ray and UV to monitor for high-energy flares while TESS simultaneously observes the transiting planet in the visible spectrum. Stellar flares like those of AU Mic can bathe planets in radiation.
Studying high-energy flares from AU Mic with Swift will help us understand the flare-rate over time, which will help with models of the planet’s atmosphere and the system’s space weather. There's even a (very) small chance for Swift to see a hint of the planet's transit!
The flares that a star produces can have a direct impact on orbiting planets' atmospheres. The high-energy photons and particles associated with flares can alter the chemical makeup of a planet's atmosphere and erode it away over time.
Another time TESS teamed up with a different spacecraft, it discovered a hidden exoplanet, a planet beyond our solar system called AU Mic b, with the now-retired Spitzer Space Telescope. That notable discovery inspired our latest poster! It’s free to download in English and Spanish.
Spitzer’s infrared instrument was ideal for peering at dusty systems! Astronomers are still using data from Spitzer to make discoveries. In fact, the James Webb Space Telescope will carry on similar study and observe AU Mic after it launches next year.
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As the Spitzer Space Telescope’s 16-year mission ends, we’re celebrating the legacy of our infrared explorer. It was one of four Great Observatories – powerful telescopes also including Hubble, Chandra and Compton – designed to observe the cosmos in different parts of the electromagnetic spectrum.
The part of the spectrum we can see is called, predictably, visible light. But that’s just a small segment of all the wavelengths of the spectrum. The Hubble Space Telescope observes primarily in the visible spectrum. Our Chandra X-ray Observatory is designed to detect (you guessed it) X-ray emissions from very hot regions of the universe, like exploded stars and matter around black holes. Our Compton Gamma Ray Observatory, retired in 2000, produced the first all-sky survey in gamma rays, the most energetic and penetrating form of light.
Infrared radiation, or infrared light, is another type of energy that we can't see but can feel as heat. All objects in the universe emit some level of infrared radiation, whether they're hot or cold. Spitzer used its infrared instrument to make discoveries in our solar system (including Saturn's largest ring) all the way to the edge of the universe. From stars being born to planets beyond our solar system (like the seven Earth-size exoplanets around the star TRAPPIST-1), Spitzer's science discoveries will continue to inspire the world for years to come.
Together, the work of the Great Observatories gave us a more complete view and understanding of our universe.
Hubble and Chandra will continue exploring our universe, and next year they’ll be joined by an even more powerful observatory … the James Webb Space Telescope!
Many of Spitzer's breakthroughs will be studied more precisely with the Webb Space Telescope. Like Spitzer, Webb is specialized for infrared light. But with its giant gold-coated beryllium mirror and nine new technologies, Webb is about 1,000 times more powerful. The forthcoming telescope will be able to push Spitzer's science findings to new frontiers, from identifying chemicals in exoplanet atmospheres to locating some of the first galaxies to form after the Big Bang.
We can’t wait for another explorer to join our space telescope superteam!
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We launched our Spitzer Space Telescope into orbit around the Sunday on Aug. 25, 2003. Since then, the observatory has been lifting the veil on the wonders of the cosmos, from our own solar system to faraway galaxies, using infrared light.
Thanks to Spitzer, scientists were able to confirm the presence of seven rocky, Earth-size planets in the TRAPPIST-1 system. The telescope has also provided weather maps of hot, gaseous exoplanets and revealed a hidden ring around Saturn. It has illuminated hidden collections of dust in a wide variety of locations, including cosmic nebulas (clouds of gas and dust in space), where young stars form, and swirling galaxies. Spitzer has additionally investigated some of the universe's oldest galaxies and stared at the black hole at the center of the Milky Way.
In honor of Spitzer's Sweet 16 in space, here are 16 amazing images from the mission.
This Spitzer image shows the giant star Zeta Ophiuchi and the bow shock, or shock wave, in front of it. Visible only in infrared light, the bow shock is created by winds that flow from the star, making ripples in the surrounding dust.
The Pleiades star cluster, also known as the Seven Sisters, is a frequent target for night sky observers. This image from Spitzer zooms in on a few members of the sisterhood. The filaments surrounding the stars are dust, and the three colors represent different wavelengths of infrared light.
Newborn stars peek out from beneath their blanket of dust in this image of the Rho Ophiuchi nebula. Called "Rho Oph" by astronomers and located about 400 light-years from Earth, it's one of the closest star-forming regions to our own solar system.
The youngest stars in this image are surrounded by dusty disks of material from which the stars — and their potential planetary systems — are forming. More evolved stars, which have shed their natal material, are blue.
Located about 700 light-years from Earth, the eye-like Helix nebula is a planetary nebula, or the remains of a Sun-like star. When these stars run out of their internal fuel supply, their outer layers puff up to create the nebula. Our Sun will blossom into a planetary nebula when it dies in about 5 billion years.
The bright star at the center of this image is Eta Carinae, one of the most massive stars in the Milky Way galaxy. With around 100 times the mass of the Sun and at least 1 million times the brightness, Eta Carinae releases a tremendous outflow of energy that has eroded the surrounding nebula.
Located 28 million light-years from Earth, Messier 104 — also called the Sombrero galaxy or M104 — is notable for its nearly edge-on orientation as seen from our planet. Spitzer observations were the first to reveal the smooth, bright ring of dust (seen in red) circling the galaxy.
This infrared image of the galaxy Messier 81, or M81, reveals lanes of dust illuminated by active star formation throughout the galaxy's spiral arms. Located in the northern constellation of Ursa Major (which includes the Big Dipper), M81 is also about 12 million light-years from Earth.
Messier 82 — also known as the Cigar galaxy or M82 — is a hotbed of young, massive stars. In visible light, it appears as a diffuse bar of blue light, but in this infrared image, scientists can see huge red clouds of dust blown out into space by winds and radiation from those stars.
This image of Messier 101, also known as the Pinwheel Galaxy or M101, combines data in the infrared, visible, ultraviolet and X-rays from Spitzer and three other NASA space telescopes: Hubble, the Galaxy Evolution Explorer's Far Ultraviolet detector (GALEX) and the Chandra X-Ray Observatory. The galaxy is about 70% larger than our own Milky Way, with a diameter of about 170,000 light-years, and sits at a distance of 21 million light-years from Earth. Read more about its colors here.
Approximately 100 million years ago, a smaller galaxy plunged through the heart of the Cartwheel galaxy, creating ripples of brief star formation. As with the Pinwheel galaxy above, this composite image includes data from NASA's Spitzer, Hubble, GALEX and Chandra observatories.
The first ripple appears as a bright blue outer ring around the larger object, radiating ultraviolet light visible to GALEX. The clumps of pink along the outer blue ring are X-ray (observed by Chandra) and ultraviolet radiation.
Located 1,500 light-years from Earth, the Orion nebula is the brightest spot in the sword of the constellation Orion. Four massive stars, collectively called the Trapezium, appear as a yellow smudge near the image center. Visible and ultraviolet data from Hubble appear as swirls of green that indicate the presence of gas heated by intense ultraviolet radiation from the Trapezium's stars. Less-embedded stars appear as specks of green, and foreground stars as blue spots. Meanwhile, Spitzer's infrared view exposes carbon-rich molecules called polycyclic aromatic hydrocarbons, shown here as wisps of red and orange. Orange-yellow dots are infant stars deeply embedded in cocoons of dust and gas.
Located about 10,000 light-years from Earth in the constellation Auriga, the Spider nebula resides in the outer part of the Milky Way. Combining data from Spitzer and the Two Micron All Sky Survey (2MASS), the image shows green clouds of dust illuminated by star formation in the region.
This view of the North America nebula combines visible light collected by the Digitized Sky Survey with infrared light from NASA's Spitzer Space Telescope. Blue hues represent visible light, while infrared is displayed as red and green. Clusters of young stars (about 1 million years old) can be found throughout the image.
This infrared mosaic offers a stunning view of the Milky Way galaxy's busy center. The pictured region, located in the Sagittarius constellation, is 900 light-years agross and shows hundreds of thousands of mostly old stars amid clouds of glowing dust lit up by younger, more massive stars. Our Sun is located 26,000 light-years away in a more peaceful, spacious neighborhood, out in the galactic suburbs.
The Large Magellanic Cloud, a dwarf galaxy located about 160,000 light-years from Earth, looks like a choppy sea of dust in this infrared portrait. The blue color, seen most prominently in the central bar, represents starlight from older stars. The chaotic, bright regions outside this bar are filled with hot, massive stars buried in thick blankets of dust.
In this large celestial mosaic from Spitzer, there's a lot to see, including multiple clusters of stars born from the same dense clumps of gas and dust. The grand green-and-orange delta filling most of the image is a faraway nebula. The bright white region at its tip is illuminated by massive stars, and dust that has been heated by the stars' radiation creates the surrounding red glow.
Managed by our Jet Propulsion Laboratory in Pasadena, California, Spitzer's primary mission lasted five-and-a-half years and ended when it ran out of the liquid helium coolant necessary to operate two of its three instruments. But, its passive-cooling design has allowed part of its third instrument to continue operating for more than 10 additional years. The mission is scheduled to end on Jan. 30, 2020.
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This composite image from our Chandra X-ray Observatory, the Spitzer Space Telescope and the Isaac Newton Telescope shows high-energy X-rays emitted by young, massive stars in the star cluster Cygnus OB2. This year we're celebrating the 20th anniversary of Chandra's launch. Want to dive deeper? Click here
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We often imagine galaxies as having massive spiral arms or thick disks of dust, but not all galaxies are oriented face-on as viewed from Earth. From our viewpoint, our Spitzer Space Telescope can detect this galaxy's infrared light but can only view the entire galaxy on its side where we can't see its spiral features. We know it has a diameter of roughly 60,000 light-years — a little more than half the diameter of our own Milky Way galaxy.
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Check out features of our feline friends that have come to life as interstellar phenomena!
Pictured first, the Cat’s Paw Nebula is located about 4,200-5,500 light-years from Earth – situated in our very own Milky Way Galaxy. It was named for the large, round features that create the impression of a feline footprint and was captured by our Spitzer Space Telescope. After gas and dust inside the nebula collapse to form stars, the stars may in turn heat up the pressurized gas surrounding them. This process causes the gas to expand into space and form the bright red bubbles you see. The green areas show places where radiation from hot stars collided with large molecules called "polycyclic aromatic hydrocarbons," causing them to fluoresce.
Next, you’ll find the Cat’s Eye Nebula. Residing 3,000 light-years from Earth, the Cat’s Eye represents a brief, yet glorious, phase in the life of a sun-like star. This nebula's dying central star may have produced the simple, outer pattern of dusty concentric shells by shrugging off outer layers in a series of regular convulsions. To create this view, Hubble Space Telescope archival image data have been reprocessed. Compared to well-known Hubble pictures, the alternative processing strives to sharpen and improve the visibility of details in light and dark areas of the nebula and also applies a more complex color palette. Gazing into the Cat's Eye, astronomers may well be seeing the fate of our sun, destined to enter its own planetary nebula phase of evolution ... in about 5 billion years.
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Image Credit:NASA/JPL-Caltech
In this large celestial mosaic, our Spitzer Space Telescope captured a stellar family portrait! You can find infants, parents and grandparents of star-forming regions all in this generational photo. There’s a lot to see in this image, including multiple clusters of stars born from the same dense clumps of gas and dust – some older and more evolved than others. Dive deeper into its intricacies by visiting https://go.nasa.gov/2XpiWLf
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