NASA's Spitzer Space Telescope is an infrared observatory that has been used to study objects from our own solar system all the way to the edge of the universe. The mission’s list of accomplishments is long and includes some of the first investigations of exoplanet atmospheres (planets around stars other than the Sun); the detection of seven Earth-size exoplanets around the TRAPPIST-1 star (the most rocky planets ever found around a single star); surprising revelations about some of the oldest galaxies in the universe; and the discovery of a new ring around Saturn. The powerful observational capabilities of this 16-year mission lifted the veil on the infrared universe.

It has been said that Spitzer was designed to study "the cold, the old and the dusty." As an infrared observatory, it can see things too cold to emit visible light, including exoplanets, brown dwarfs, comets and asteroids. With its ability to view objects that are very far away, Spitzer is able to peer into our universe's deep past. And its observations of dust — a substance prevalent throughout most galaxies and mixed with gas in clouds from which stars and planets are born — reveals physical features and morphologies that often can't be seen in other wavelengths of light. Spitzer's science investigations have yielded hundreds of breathtaking images over its long lifetime, and its spectroscopic capabilities provide insights into the chemical compositions of the telescope's targets.

Over the past 16 years, thousands of scientists from around the world have conducted observations with Spitzer, and over 8,600 papers (and counting) have been published using the workhorse observatory's data. All the data that the telescope has compiled during its lifetime will remain in a publicly accessible archive for the foreseeable future. Astronomers already use that archive for new analyses and to complement work by other observatories, and they're expected to continue doing so long after the spacecraft has been decommissioned.

15 of Spitzer's Greatest Discoveries From 15 Years in Space:

Solar System, Comets and Asteroids

• Spitzer measures the chemical composition of comet dust. The dust was kicked up by NASA’s Deep Impact mission and provided scientists with a “recipe for comet soup.” (2005) https://www.jpl.nasa.gov/news/news.php?release=2005-144
• Spitzer identifies a new ring around Saturn. This gigantic ring is composed of extremely small and sparsely distributed particles that reflect very little visible light, which explains how it stayed hidden for so long. (2009) https://www.jpl.nasa.gov/news/news.php?release=2009-150
• NASA Learns More About Interstellar Visitor 'Oumuamua (2018) https://www.jpl.nasa.gov/news/news.php?feature=7280
• Spitzer Finds a Flavorful Mix of Asteroids (2010) https://www.jpl.nasa.gov/news/news.php?feature=2719

Star formation and birth, giant molecular clouds and nebulas

• Two Peas in an Irregular Pod Reveal How Binary Stars May Form (2010) http://www.spitzer.caltech.edu/news/1123-feature10-07-Two-Peas-in-an-Irregular-Pod-How-Binary-Stars-May-Form
• NASA Satellites Catch a 'Growth Spurt' from a Newborn Protostar (2015) https://www.jpl.nasa.gov/news/news.php?feature=4518M
• NASA, ESA Telescopes Find Evidence for Asteroid Belt Around Vega (2013) https://www.jpl.nasa.gov/news/news.php?feature=3647
• Planet-Forming Disks Might Put the Brakes on Stars (2006) https://www.nasa.gov/centers/jpl/news/spitzer-20060724.html
• NASA Space Telescopes Provide a 3-D Journey Through the Orion Nebula (2018) https://www.jpl.nasa.gov/news/news.php?feature=7035
• Horsehead of a Different Color (2014) https://www.jpl.nasa.gov/news/news.php?feature=4419
• A Space Spider Watches Over Young Stars (2016) https://www.jpl.nasa.gov/news/news.php?feature=6422
• The Fading Ghost of a Long-Dead Star (2018) https://www.jpl.nasa.gov/news/news.php?feature=7207
• Spitzer Spots a Starry Region Bursting With Bubbles (2019) https://www.jpl.nasa.gov/news/news.php?feature=7507
• NASA's Spitzer Captures Stellar Family Portrait (2019) https://www.jpl.nasa.gov/news/news.php?feature=7413
• 'Space Butterfly' Is Home to Hundreds of Baby Stars (2019) https://www.jpl.nasa.gov/news/news.php?feature=7359
• Newborn Stars Blow Bubbles in the Cat's Paw Nebula (2018) https://www.jpl.nasa.gov/news/news.php?feature=7265

Protoplanetary disks and the formation of planetary systems:

• Spitzer shows that planets can form around young stars much sooner than previously predicted. Observations suggest planets can pop up like wildflowers less than one million years after the formation of the parent star. (2005) https://www.jpl.nasa.gov/news/news.php?feature=2150
• Spitzer observes evidence of asteroid collisions in a dust disk around a star. These smashups may be critical to the eventual formation of planets in these disks. (2014) https://www.jpl.nasa.gov/news/news.php?feature=4273
• Spitzer finds that hot stellar flares produce tiny silicate crystals found in frozen comets. This discovery helped solve a mystery about how the crystals, which form at high temperatures, found their way into comets, which are born in the deep freeze of the solar system's outer edges. (2009) https://www.jpl.nasa.gov/news/news.php?feature=2150
• Spitzer finds multiple “dead stars” (called white dwarfs) surrounded by the remains of shredded asteroids. The results suggest that the same materials that make up Earth and our solar system's other rocky bodies could be common in the universe. If the materials are common, then rocky planets could be, too. https://www.nasa.gov/mission_pages/spitzer/news/spitzer-20090105.html
• Pulverized Planet Dust May Lie Around Double Stars (2010) https://www.jpl.nasa.gov/news/news.php?release=2010-275
• Spitzer Finds Organics and Water Where New Planets May Grow (2008) https://www.jpl.nasa.gov/news/news.php?feature=1635
• Light Echoes Give Clues to Protoplanetary Disk (2016) https://www.jpl.nasa.gov/news/news.php?feature=6439
• Closest Planetary System Hosts Two Asteroid Belts (2008) https://www.jpl.nasa.gov/news/news.php?feature=1914
• Youthful Star Sprouts Planets Early (2007) https://www.jpl.nasa.gov/news/news.php?feature=1535
• Follow the Dust to Find Planets (2014) https://www.jpl.nasa.gov/news/news.php?feature=4368

Exoplanets (planets outside our solar system):

• Spitzer identifies the largest number of rocky exoplanets ever found around a single star. The TRAPPIST-1 star hosts seven planets — all of them terrestrial, like Earth. Previous studies by a ground-based telescope had identified three planets in the system. (2017) https://exoplanets.nasa.gov/news/1419/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around-single-star/
• Spitzer makes the first detection of light directly from an exoplanet. Previously, scientists had detected the presence of exoplanets only through indirect means, such as by observing when a planet blocks the light from its parent star. (2005) https://www.jpl.nasa.gov/news/news.php?feature=757
• Spitzer makes the first identification of molecules in an exoplanet's atmosphere. The gaseous planet is similar to Saturn or Jupiter but extremely hot. (2007) https://www.jpl.nasa.gov/news/news.php?feature=1297
• Spitzer scientists produce the first ever “weather map” for an exoplanet atmosphere. This marks the first detection of temperature variations and the presence of wind in a planet’s atmosphere. (2007) https://www.jpl.nasa.gov/news/news.php?release=2007-055
• Spitzer and a ground-based telescope locate one of the most distant exoplanets ever found. The observatories use a technique called microlensing, which is useful for searching for planets far away from our Sun, as well as planets that orbit far away from their parent star. (2007) https://www.jpl.nasa.gov/news/news.php?feature=4550
• Astronomers Find Planet Hotter Than Most Stars (2017) https://www.jpl.nasa.gov/news/news.php?feature=6865
• NASA's Spitzer Confirms Closest Rocky Exoplanet (2015) https://www.jpl.nasa.gov/news/news.php?feature=4672
• 'Iceball' Planet Discovered Through Microlensing (2017) https://www.jpl.nasa.gov/news/news.php?feature=6827
• Lava or Not, Exoplanet 55 Cancri e Likely to Have Atmosphere (2017) https://www.jpl.nasa.gov/news/news.php?feature=7001
• NASA's Spitzer Maps Climate Patterns on a Super-Earth (2016) https://www.jpl.nasa.gov/news/news.php?feature=6223

Stellar evolution, star death, low mass stars and brown dwarfs:

• The Shocking Behavior of a Speedy Star (2014) http://jpl.nasa.gov/news/news.php?feature=4054
• A Confetti-Like Collection of Stars (2013) https://www.jpl.nasa.gov/news/news.php?feature=3752
• Observatories Combine to Crack Open the Crab Nebula (2017) https://www.jpl.nasa.gov/news/news.php?feature=6842
• Stormy Stars? NASA's Spitzer Probes Weather on Brown Dwarfs (2014) https://www.jpl.nasa.gov/news/news.php?release=2014-005
• NASA's Spitzer and WISE Telescopes Find Close, Cold Neighbor of Sun (2014) nasa.gov/jpl/wise/spitzer-coldest-brown-dwarf-20140425
• Mysterious Dimming of Tabby's Star May Be Caused by Dust (2017) https://www.jpl.nasa.gov/news/news.php?feature=6925

Interstellar molecules and dust:

• Spitzer makes the first detection of buckyballs (uniquely structured carbon molecules) in space. Belonging to a class of molecules known as buckminsterfullerenes, or fullerenes, they are a marvel of nature, with applications in medicine, engineering and energy storage. (2010) https://www.jpl.nasa.gov/news/news.php?release=2010-243

Quasars/active galactic nuclei/supermassive black holes:

• Spitzer identifies two of the most distant black holes ever found. Quasars are galaxies with supermassive black holes at their centers; the very hot material around the black hole radiates so brightly that it can outshine all the stars in the galaxy and be seen across the visible universe. (2010) https://www.jpl.nasa.gov/news/news.php?feature=2520
• The Giant Galaxy Around the Giant Black Hole (2019) https://www.jpl.nasa.gov/newws/news.php?feature=7385
• NASA's Spitzer Unearths Primitive Black Holes (2010) https://www.jpl.nasa.gov/news/news.php?feature=2520
• Astronomers See Distant Eruption as Black Hole Destroys Star (2018) https://www.jpl.nasa.gov/news/news.php?feature=7162
• NASA Telescopes Find Clues for How Giant Black Holes Formed So Quickly (2016) https://www.jpl.nasa.gov/news/news.php?feature=6517
• NASA's WISE Survey Uncovers Millions of Black Holes (2012) https://www.jpl.nasa.gov/news/news.php?feature=3496
• Missing Black Hole Report: Hundreds Found! (2007) https://www.jpl.nasa.gov/news/news.php?feature=1508

Galaxy evolution and ancient/distant galaxies:

• Spitzer and NASA’s Hubble Space Telescope “weigh” some of the most distant galaxies ever observed and find them heavier than expected. These “big baby” galaxies changed ideas about how the first galaxies formed in our universe. (2005) https://www.jpl.nasa.gov/news/news.php?feature=946
• NASA's Spitzer Telescope Brings 360-Degree View of Galaxy to Our Fingertips (2014) https://www.jpl.nasa.gov/news/news.php?feature=4085
• Planet Smash-Up Sends Vaporized Rock, Hot Lava Flying (2009) https://www.nasa.gov/mission_pages/spitzer/news/spitzer-20090810.html
• New Clues About How Ancient Galaxies Lit Up the Universe (2019) https://www.jpl.nasa.gov/news/news.php?feature=7397
• The Frontier Fields: Where Primordial Galaxies Lurk (2016) https://www.jpl.nasa.gov/news/news.php?feature=6629
• NASA Observatories Find Most Distant Galaxy Candidate (2012) https://www.jpl.nasa.gov/news/news.php?feature=3589
• Astronomers Discover Colossal 'Super Spiral' Galaxies (2016) https://www.jpl.nasa.gov/news/news.php?feature=6149

Galaxy clusters:

• Spitzer and four other telescopes enable scientists to identify one of the most distant (and therefore oldest) protocluters ever found. Protoclusters are collections of galaxies in the process of forming a cluster, which is a group of galaxies bound together by gravity. More than half of nearby galaxies belong to clusters, and this discovery contributes to an understanding of how the large-scale structure of our universe has evolved over time. (2011) https://www.jpl.nasa.gov/news/news.php?feature=2875
• Whopping Galaxy Cluster Spotted With Help of NASA Telescopes (2015) https://www.jpl.nasa.gov/news/news.php?feature=4762
• NASA Telescopes Help Identify Most Distant Galaxy Cluster (2011) https://www.jpl.nasa.gov/news/news.php?feature=2875