One of NASA’s original great observatories, Spitzer showed us the infrared Universe as never before.
On January 30, 2020,
NASA’s Spitzer Space Telescope was retired after a 17 year mission.
Prior to its 2003 launch, Spitzer was completed on the ground and installed inside a Delta II rocket at Kennedy Space Center. This photo was taken on August 14, 2003. (NASA)
Along with Hubble, Compton, and Chandra, Spitzer was the final of
NASA’s Great Observatories.
The fourth and final element in NASA’s family of orbiting Great Observatories, Spitzer was successfully launched from Launch Pad 17-B at Cape Canaveral on August 25, 2003. (NATIONAL AERONAUTICS AND SPACE ADMINISTRATION)
Owing to its location above Earth’s atmosphere, its measurement capabilities were unique.
The transmittance or opacity of the electromagnetic spectrum through the atmosphere. Note all the absorption features in gamma rays, X-rays, and the infrared, which is why the greatest of our observatories in these wavelength are all located in space. The infrared, in particular, was spectacularly covered by NASA’s Spitzer, and will be again by James Webb. (NASA)
Until James Webb launches, Spitzer remains humanity’s greatest mid-infrared observatory.
The James Webb Space Telescope vs. Hubble in size (main) and vs. an array of other telescopes (inset) in terms of wavelength and sensitivity. It should be able to see the truly first galaxies, the earliest, most pristine stars, the smallest directly imaged planets and more. Its power is truly unprecedented, as it’s more than an order of magnitude better than Spitzer across all relevant wavelengths. (NASA / JWST SCIENCE TEAM)
These 22 images
highlight its greatest achievements.
This rather unspectacular-looking ‘dot’ of light is from a tiny portion of the galaxy NGC 4993, which corresponds to the location of the first neutron star-neutron star merger ever detected in gravitational waves. This is the last image of the infrared afterglow of the event ever to be imaged, as captured by Spitzer on October 16, 2017. (NASA/JPL-CALTECH)
Among them, Spitzer excelled at measuring:
The flame Nebula, shown here in a combination of X-ray data (from Chandra) and infrared light (from Spitzer), showcases a young, massive star cluster at the center which carves out a spectacular shape in the surrounding gaseous material that was used for star-formation. Spitzer, in combination with the other great observatories, has helped us come up with superior models of star-formation than would have been possible without this data. (X-RAY: NASA/CXC/PSU/K.GETMAN, E.FEIGELSON, M.KUHN & THE MYSTIX TEAM; INFRARED:NASA/JPL-CALTECH)
ultra-distant objects whose light is severely redshifted,
The most distant galaxy ever discovered in the known Universe, GN-z11, has its light come to us from 13.4 billion years ago: when the Universe was only 3% its current age: 407 million years old. The distance from this galaxy to us, taking the expanding Universe into account, is an incredible 32.1 billion light-years, and is only possible because of a serendipitous lack of light-blocking dust along the line-of-sight to this galaxy. A combination of Hubble and Spitzer observations were used to discover this galaxy, whose light is so severely redshifted that it only appears in the infrared portion of the spectrum. (NASA, ESA, AND G. BACON (STSCI))
cool objects which emit very little optical light,
Three separate regions illustrate various stages of a newly forming star’s life, which are totally obscured in the optical and can only be seen in the infrared. At left, a protostar emits radiation that’s shrouded in light-blocking dust. In the center, a ‘yellowball’ announces the start of nuclear fusion, but still cannot be seen in the optical due to all the surrounding matter. At right, a more evolved star has begun to blow an ionized bubble in the surrounding region. Spitzer has shed new light on how stars form. (NASA/JPL-CALTECH)
obscured objects located behind light-blocking dust,
Clumps of matter can be so dense that not even infrared light can penetrate them. They cast the deepest shadows of all, and Spitzer captured some of them here (in silhouette) against a backdrop of massive, newly forming stars. The white clumps are where the detector has been saturated, and are likely the locations of the newest, bluest, most massive stars of all: O-class stars, which will likely all end their lives in supernova explosions in just a few million years. (NASA/JPL-CALTECH)
As they orbit the Sun, comets and asteroids can break up a little bit, with debris between the chunks along the path of the orbit getting stretched out over time, and causing the meteor showers we see when the Earth passes through that debris stream. This image taken by Spitzer along a comet’s path shows small fragments outgassing, but also shows the main debris stream that gives rise to the meteor showers that occur in our Solar System. (NASA / JPL-CALTECH / W. REACH (SSC/CALTECH))
interstellar gas that’s heated by nearby stars,
Newborn stars that are just now forming light up the nebula NGC 2174, 6,400 light-years away, as imaged in the infrared by Spitzer. The warm dust that surrounds them glows in a variety of colors, while the coolest, red regions point to locations where star formation is likely still ongoing. (NASA/JPL-CALTECH)
remnants and ejecta from dying or recently deceased stars,
The supernova remnant 1E0102.2–7219 (inset) sits next to the nebula N76 in a bright, star-forming region of the Small Magellanic Cloud. This supernova remnant is composed of the material ejected from the death of the predecessor star, with Spitzer’s infrared eyes helping us understand how the X-rays reveal a reverse shock as it slams into stellar material that was expelled during the explosion. (NASA/JPL-CALTECH/S. STANIMIROVIC (UC BERKELEY))
including supernovae and remnants,
In February of 2014, a supernova went off in the dusty, nearby galaxy of Messier 82: the Cigar galaxy. Spitzer’s infrared eyes can successfully penetrate the dust, allowing it to observe and follow the evolution of the light from this transient object. (NASA/JPL-CALTECH)
This infrared view of supernova remnant RCW 86 highlights the dusty remains of all that’s left of an ancient supernova that’s thousands of years old: the earliest documented example of a supernova visible in our night sky. (NASA/JPL-CALTECH/B. WILLIAMS (NCSU))
as well as planetary nebulae,
These three planetary nebulae, all imaged by Spitzer, highlight features inherent to dying Sun-like stars. From left to right, the Exposed Cranium Nebula, the Ghost of Jupiter Nebula, and the Little Dumbbell Nebula all exhibit stellar winds, ejected material consisting of different elements, and a central, luminous stellar remnant. (NASA/JPL-CALTECH/J. HORA (HARVARD-SMITHSONIAN CFA))
the last extended embers of dying Sun-like stars,
This combined image from NASA’s Spitzer Space Telescope and the ultraviolet Galaxy Evolution Explorer (GALEX). 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. Spitzer reveals many different aspects of the stellar ejecta, now illuminated by the central white dwarf. (NASA/JPL-CALTECH)
as well as mapping specific elements found in nearby galaxies.
This infrared portrait of the Small Magellanic Cloud, located just 199,000 light-years away, highlights a variety of features, including new stars, cool gas, and quite spectacularly (in green) the presence of polycyclic aromatic hydrocarbons: the most complex organic molecules ever found in the natural environment of interstellar space. (NASA/JPL-CALTECH/K. GORDON (STSCI))
Interacting galaxies are doubly spectacular.
A mix of stars (in blue and green) and warm dust (in red) are revealed in this Spitzer composite image of the interacting galaxy pair known as Arp 86. The rich red features trace out the locations of future sites of star-formation. (NASA/JPL-CALTECH)
This infrared view of the Whirlpool Galaxy, Messier 51, reveals a plethora of active star formation and heated gas/dust lining the spiral arms. A gas bridge is being pulled from one of the extended spiral arms towards the interacting galactic companion, which itself is gas-poor and doesn’t show the same evidence of star formation. (NASA/JPL-CALTECH)
extended star formation,
This spectacular image was created with composite Spitzer and Hubble data, and shows a tidally distorted galaxy, rich in gas and actively forming new stars, merging with an old, gas-free elliptical galaxy made up of older stars. Poetically, this is called ‘the penguin and the egg.’ (NASA-ESA/STSCI/AURA/JPL-CALTECH)
and dead, quiet galaxies all appear.
An example of a very rare ring galaxy, NGC 1291, showcases an outer galaxy that’s rich in gas and forming new stars surrounding an old, quiet center that is virtually gas-free and has scant evidence of new star formation. Both gas-rich and gas-poor galaxies are found throughout the Universe, and Spitzer’s infrared eyes are ultra-sensitive to them. (NASA/JPL-CALTECH)
Spitzer also offered a unique perspective on otherwise familiar objects.
This infrared view of the plane of the Milky Way, taken from space by NASA’s Spitzer as part of the GLIMPSE galactic survey, is one of the most ambitious observing projects ever undertaken, taking a decade to complete. At longer wavelengths than are visible from the ground, the gas of different temperatures from our galaxy is highlighted as never before, revealing details about our home galaxy than cannot be seen in any other set of wavelengths. (NASA/JPL-CALTECH/UNIVERSITY OF WISCONSIN)
Messier 83 shows a miniature Milky Way.
This infrared view of Messier 83, also known as the Southern Pinwheel Galaxy, is a miniature version of the Milky Way, about half of our size but with spiral arms, rich gas, and a central bar that extends for thousands of light-years. This infrared view helps us understand how the gas and dust in our own galaxy, which we can only see edge-on, might be distributed. (NASA/JPL-CALTECH)
Visible jets appear around M87’s supermassive black hole.
Messier 87, best known as the supermassive galaxy whose black hole was first imaged by the Event Horizon Telescope, has its relativistic jets and the shockwaves created by their material imaged in the infrared by Spitzer, amidst the mass of shining stars (in blue). (NASA/JPL-CALTECH/IPAC)
The Crab Nebula looks vaguely familiar,
This infrared view of the Crab Nebula, from Spitzer, represents a nearly 1,000 year old supernova remnant. The infrared image reveals a cloud of energetic electrons (in blue) trapped by the central neutron star’s magnetic field, along with filamentary structures (in red) that glow at mid-infrared wavelengths. This nebula, about 5 light-years across, looks extremely different from the familiar visible light image. (NASA/JPL-CALTECH/R. GEHRZ (UNIVERSITY OF MINNESOTA))
much like the Orion Nebula.
This infrared view of the Orion Nebula, unlike the visible light view, highlights the great cavities formed when active areas of star-formation cause ultraviolet light to evaporate large amounts of star-forming material, heating the gas inside, which then becomes rich in infrared radiation due to the increased temperatures. Spitzer took this composite image in a variety of wavelengths, with blues, greens and whites corresponding to higher temperatures and reds to lower temperatures. (NASA/JPL-CALTECH/T. MEGEATH (UNIVERSITY OF TOLEDO, OHIO))
Farewell, Spitzer, and thanks for all the science.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more. Ethan Siegel is the author of
Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.