The Hubble Space Telescope is one of the largest astronomical telescopes ever sent into space. It dramatically altered the way in which we view our universe.

From its vantage point high above Earth's obscuring atmosphere, the telescope provides astronomers with fascinating new information on the universe.

Repairing Hubble

Launched from Space Shuttle Discovery in 1990, the telescope was initially hampered by a defectively shaped main mirror. During a 1993 repair mission, Shuttle astronauts installed COSTAR, a device that resolved the problem, and scientists were finally able to make full use of the telescope’s incredible capabilities.


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Soon after its launch in 1990, scientists realized that the Hubble Space Telescope’s large primary mirror was flawed. It distorted images and data, making everything blurry. A Shuttle crew installed this corrective optics package, called COSTAR (Corrective Optics Space Telescope Axial Replacement), in 1993 and returned it to Earth in 2009 when it was replaced with the  Cosmic Origins Spectrograph.

COSTAR's long box holds a clever device: tiny nickel-size mirrors that extended on short arms into the light path inside the telescope. These mirrors were precisely shaped to cancel the flaw in the large main mirror, and precisely positioned to send corrected, focused light into three instruments. A new fourth instrument, a wide-field camera, came with its own built-in corrective optics. COSTAR was an ingenious solution to the unexpected challenge of correcting the Hubble’s distorted vision.

View COSTAR's record

Hubble's Images

Hubble images serve both scientific and cultural purposes. Technicians at the Space Telescope Science Institute, where the Hubble images are processed, employ both science and artistry to color and orient the data they receive from the telescope. The vibrant and stunning Hubble images released to the public often reflect what their makers want us to understand about an object, rather than how the object would actually appear to our eyes.

How Hubble changed the way we picture our universe

For ten consecutive days in December 1995, the Hubble Space Telescope looked deep into space—and back in time. Using the Wide Field and Planetary Camera 2, scientists took 342 separate exposures that they assembled into one image: the Hubble Deep Field.

Covering a patch of sky only about the width of a dime as seen from 23 meters (75 feet) away, the Hubble Deep Field revealed at least 1,500 galaxies in various stages of evolution. “As the images have come up on our screens,” Hubble director Robert Williams said, “we have not been able to keep from wondering if we might somehow be seeing our own origins in all of this.”

More about seeing early galaxies

According to NASA: 

The brilliant tapestry of young stars flaring to life resemble a glittering fireworks display in this Hubble Space Telescope archival image.

The sparkling centerpiece of this fireworks show is a giant cluster of thousands of stars called Westerlund 2. The cluster resides in a raucous stellar breeding ground known as Gum 29, located 20,000 light-years away from Earth in the constellation Carina.

Hubble's Wide Field Camera 3 pierced through the dusty veil shrouding the stellar nursery in near-infrared light, giving astronomers a clear view of the nebula and the dense concentration of stars in the central cluster. The cluster measures between 6 light-years and 13 light-years across.

The giant stellar grouping is only about 2 million years old and contains some of our Milky Way galaxy's hottest, brightest, and most massive stars. Some of its heftiest stars unleash torrents of ultraviolet light and hurricane-force winds of charged particles that etch away the enveloping hydrogen gas cloud. New Hubble observations are showing that lower-mass stars near the cluster's core do not have the large, dense clouds of dust that eventually could become planets in a few million years. Hubble detected those planet-forming clouds embedded in disks encircling lower-mass stars farther away from the center.

The nebula reveals a landscape of pillars, ridges, and valleys. The pillars, composed of dense gas and thought to be incubators for new stars, are a few light-years tall and point to the central star cluster. Other dense regions surround the pillars, including reddish-brown filaments of gas and dust. The red dots scattered throughout the landscape are a rich population of newly forming stars still wrapped in their gas-and-dust cocoons. The brilliant blue stars seen throughout the image are mostly foreground stars.

The image's central region, which contains the star cluster, blends visible-light data taken by Hubble's Advanced Camera for Surveys with near-infrared exposures taken by the Wide Field Camera 3. The surrounding region is composed of visible-light observations taken by the Advanced Camera for Surveys. The red colors in the nebulosity represent hydrogen; the bluish-green hues are predominantly oxygen.

According to NASA:

Resembling a wide-brimmed hat with a tall bulge at the center, galaxy M104 is nicknamed the Sombrero Galaxy. Far larger than any hat on Earth, this Sombrero is 50,000 light-years wide. We see the galaxy nearly edge-on, so the dark dust in its pancake-like disk appears to bisect a large, white, rounded core of stars. Roughly 29 million light-years away, the Sombrero can be spotted with a modest telescope in the constellation Virgo.

Using Hubble, a team of astronomers led by John Kormendy of the University of Hawaii found evidence of a supermassive black hole at the center of the Sombrero Galaxy. Estimated to be as massive as a billion Suns, it's one of the heftiest black holes in the neighboring universe.

Hubble observations also reveal that the Sombrero Galaxy includes nearly 2,000 globular clusters — 10 times more than in our galaxy. Globular clusters are giant, spherical-shaped groups of stars that are sometimes older than the galaxy in which they reside. The Sombrero's globular clusters range from 10 billion to 13 billion years old, similar to those in the Milky Way.

Several teams of astronomers have used Hubble and telescopes on the ground to study the Sombrero's globular clusters. They've found that some clusters are rich in elements heavier than helium (which astronomers call "metals") and some are poor. Among other findings, the observations reveal that the "metal-rich" clusters are concentrated in the galaxy's bulge and that they are typically smaller than the "metal-poor" ones. Such studies are helping astronomers figure out how ancient globular clusters developed early in the universe's history.

According to NASA: 

Saturn is truly the lord of the rings in this latest snapshot from NASA's Hubble Space Telescope, taken on July 4, 2020, when the opulent giant world was 839 million miles from Earth. This new Saturn image was taken during summer in the planet's northern hemisphere.

Hubble found a number of small atmospheric storms. These are transient features that appear to come and go with each yearly Hubble observation. The banding in the northern hemisphere remains pronounced as seen in Hubble's 2019 observations, with several bands slightly changing color from year to year. The ringed planet's atmosphere is mostly hydrogen and helium with traces of ammonia, methane, water vapor, and hydrocarbons that give it a yellowish-brown color.

Hubble photographed a slight reddish haze over the northern hemisphere in this color composite. This may be due to heating from increased sunlight, which could either change the atmospheric circulation or perhaps remove ices from aerosols in the atmosphere. Another theory is that the increased sunlight in the summer months is changing the amounts of photochemical haze produced. "It's amazing that even over a few years, we're seeing seasonal changes on Saturn," said lead investigator Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Conversely, the just-now-visible south pole has a blue hue, reflecting changes in Saturn's winter hemisphere.

Hubble's sharp view resolves the finely etched concentric ring structure. The rings are mostly made of pieces of ice, with sizes ranging from tiny grains to giant boulders. Just how and when the rings formed remains one of our solar system's biggest mysteries. Conventional wisdom is that they are as old as the planet, over 4 billion years. But because the rings are so bright – like freshly fallen snow – a competing theory is that they may have formed during the age of the dinosaurs. Many astronomers agree that there is no satisfactory theory that explains how rings could have formed within just the past few hundred million years. "However, NASA's Cassini spacecraft measurements of tiny grains raining into Saturn's atmosphere suggest the rings can only last for 300 million more years, which is one of the arguments for a young age of the ring system," said team member Michael Wong of the University of California, Berkeley.

Two of Saturn's icy moons are clearly visible in this exposure: Mimas at right, and Enceladus at bottom.

This image is taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system's gas giant planets. In Saturn's case, astronomers continue tracking shifting weather patterns and storms.

According to NASA: 

To kick off Hubble's 25th year in orbit, astronomers used the venerable telescope to revisit one of its most iconic subjects, the so-called "Pillars of Creation" in the Eagle Nebula (M16). Three towers of gas and dust, standing light-years tall, are giving birth to new stars, buried within their dusty spires.

The pillars became famous after Hubble first imaged them in 1995 using the Wide-Field Planetary Camera 2. The features were observed again in late 2014 with that instrument' more advanced replacement, the Wide Field Camera 3. With its higher resolution, the new camera provides a sharper view of the pillars and also presents a wider vista, showing the base of the pillars and more of the region surrounding them.

In addition, the new observations captured a portrait of the pillars in infrared light, as well as in visible light. The longer wavelengths of infrared light pass more easily through the dusty environs, allowing us to see more of the wispy details and the stars normally hidden inside or behind the pillars when viewed in visible light.

By comparing Hubble's original image of the pillars to the new one, astronomers also noticed changes in a jet-like feature shooting away from one of the newborn stars within the pillars. The jet grew 60 billion miles longer in the time between observations, suggesting material in the jet was traveling at a speed of about 450,000 miles per hour.

Such observations of the details and changes in the pillars of the Eagle Nebula, and of observations near and far throughout the universe, have been made possible by Hubble’s viewpoint beyond Earth's atmosphere, by its technical upgrades over the years, and the longevity of its career.

Reflecting on Hubble's Work

Launched over 30 years ago, experts reflect on what the Hubble Telescope has taught us over the decades.

Hubble at 30 Watch 'Hubble at 30' Live Chat: Hubble at 30 More 'Hubble at 30' Telling Hubble's Story for 30 Years Read about Hubble at 30 How Hubble Paved the Way for the Future

The Hubble Space Telescope is opening new frontiers of astronomical discovery, even decades after its launch, thanks to its suite of cameras and spectrographs, five astronaut servicing missions, and innovative uses by scientists around the world. In this lecture, Jennifer Wiseman, Hubble Space Telescope senior project scientist at NASA’s Goddard Space Flight Center, will highlight Hubble’s newest incredible observations of stars, distant galaxies, and even planets outside our solar system. She will also discuss how Hubble is being used for clever investigations of mysterious dark matter, dark energy, and black holes. With the imminent launch of the James Webb Space Telescope (JWST), the Hubble mission is now placing special emphasis on observations that will set the stage for the most effective uses of JWST. 

Watch Hubble lecture
The Mother of Hubble

Nancy Grace Roman began working on the question of putting astronomical instruments into space as early as 1962, puzzling about how an accurate pointing system could be incorporated on a telescope or detector that would be small enough to be launched by the rockets of the day. Her advocacy for putting the tools of astronomy in space, beyond the blurring effects of the Earth’s atmosphere, eventually led to the Hubble Space Telescope. 

Learn more about the Mother of Hubble

In the Collection

Hubble Space Telescope Object Model, 1:5, Hubble Space Telescope Object Manipulator Foot Restraint and Grapple Fixture, Shuttle, Hubble Space Telescope Object Camera, HST, Wide Field-Planetary, F/30 Sensor Head/Relay Optics, #7 Object

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The National Air and Space Museum gratefully acknowledges the generosity of the Lockheed Missiles and Space Company for donating this artifact and supporting its initial restoration. The test vehicle was refurbished for this exhibit by Lockheed Martin Missiles and Space, Lockheed Martin Technical Operations, Jackson and Tull, NSI Technology Services, Swales & Associates, Hughes Danbury Optical Systems, and NASA's Goddard Space Flight Center.