Since its launch in 1990, the Hubble Space Telescope (HST) has provided a dazzling array of images that have awed and inspired the public. More than just pretty pictures, the dozens of terabytes of data collected has provided insight into the universe, from objects as close as the moon to the most remote galaxies, with incredible photos of supernovas and nebulas in between. 

Below we explore the history of the telescope and its discoveries, plus Hubble facts and links to some of the orbiting observatory's best pictures. First, we take a look at an iconic photo. No Hubble picture is more widely recognized than the view of the so-called Pillars of Creation within the Eagle Nebula. [See a gallery of recent Hubble pictures.]

This 1995 Hubble Space Telescope image of the 'Pillars of Creation' is probably the most famous astronomical image of the 20th Century. Taken in visible light using a combination of SII/H-alpha and OIII filters, it shows a part of the Eagle Nebula where new stars are forming. The tallest pillar is around 4 light-years high.
This 1995 Hubble Space Telescope image of the 'Pillars of Creation' is probably the most famous astronomical image of the 20th Century. Taken in visible light using a combination of SII/H-alpha and OIII filters, it shows a part of the Eagle Nebula where new stars are forming. The tallest pillar is around 4 light-years high.
Credit: NASA/ESA/STScI, Hester & Scowen (Arizona State University)

The telescope initially launched with a flaw in its mirror that hampered its ability to do observations. This caused much consternation among the scientific community, given that Hubble cost $1.5 billion in 1990 dollars (approximately $2.87 billion in 2017 dollars.) But following a successful shuttle repair mission in 1993, the reputation of Hubble recovered and today it is one of the most famous telescopes ever.

With the completion of the last servicing mission in 2009, Hubble remains in good health and is pegged to continue operations well past the launch of a successor observatory – the James Webb Space Telescope – in 2019.

When Galileo first turned a spyglass to the heavens in 1610, he had trouble making out the rings of Saturn that are visible in inexpensive telescopes today. Advances in optics improved scientists' views of the planets, stars, and distant galaxies, but Earth's atmosphere still blocked much of the light for observers on the ground. Larger telescopes were (and still are) placed on high mountains, where thinner atmospheres allow clearer pictures.

In 1923, German scientist Hermann Oberth first suggested that a telescope could be launched into orbit to help overcome the distortions caused by the atmosphere. As rocket launchings became more commonplace, the idea became feasible, and in 1969, approval was given for the launch of a Large Space Telescope. But its development took longer than preparing for a trip to the moon.

In 1975, the European Space Agency began to work with NASA on the plan that would eventually become Hubble. Congress approved funding for the telescope in 1977. The birth of the reusable Space Shuttle provided a new mechanism for delivering such a telescope into space.

The Large Space Telescope was renamed the Hubble (HST) in honor of Edwin Hubble, an American astronomer who, among other things, determined that the universe extended beyond the borders of Milky Way. The world's first space telescope was then launched on April 24, 1990. The effort cost $1.5 billion, but there would be ongoing costs — both expected and unexpected.

Initial instruments on Hubble included the Wide Field Planetary Camera, the Goddard High Resolution Spectrograph (GHRS), the Faint Object Camera (FOC), the Faint Object Spectrograph (FOS) and the High Speed Photometer. Butthere was a big problem right off the bat. Hubble had a flawed mirror, researchers learned when the telescope reached orbit and was put to work. The images were fuzzy — close to useless. Hubble's main mirror had a major defect, a spherical aberration caused by a manufacturing error. The flaw was just 1/50th the thickness of a sheet of paper.

It took three years before NASA could mount a repair mission. On Dec. 2, 1993, the Space Shuttle Endeavor ferried a crew of seven to fix Hubble during five days of spacewalks. Two new cameras, including the Wide-Field Planetary Camera 2 (WFPC-2) — which later took many of Hubble's most famous photos — were installed during the fix. In December 1993, the first new images from Hubble reached Earth. And they were breathtaking.

The Hubble is a joint project between NASA and the European Space Agency. Here are some basic facts about the telescope and the mission, courtesy the Space Telescope Science Institute (STScI), which operates Hubble for NASA:

Telescope size

  • Length: 43.5 feet (13.2 meters)
  • Weight: 24,500 lbs. (11,110 kilograms)
  • Maximum diameter: 14 feet (4.2 m)

Mission facts

  • Launch: April 24, 1990, from space shuttle Discovery (STS-31)
  • Deployment: April 25, 1990
  • Servicing Mission 1: December 1993
  • Servicing Mission 2: February 1997
  • Servicing Mission 3A: December 1999
  • Servicing Mission 3B: February 2002
  • Servicing Mission 4: May 2009

Spaceflight stats

  • Orbit: Average altitude of 307 nautical miles (569 km, or 353 miles), inclined 28.5 degrees to the equator.
  • Time to complete one orbit: 97 minutes
  • Speed: 17,500 mph (28,000 km/h)

Data

Hubble transmits about 120 gigabytes of science data every week. That would be roughly 3,600 feet (1,097 m) of books on a shelf. The collection of pictures and data is stored on magneto-optical disks.

Power

  • Energy source: the sun
  • Mechanism: Two 25-foot solar panels
  • Power usage: 2,800 watts
  • Batteries: 6 nickel-hydrogen (NiH), with a storage capacity equal to 20 car batteries

Optics

  • Primary mirror diameter: 94.5 in (2.4 m)
  • Primary mirror weight: 1,825 lb (828 kg)
  • Secondary mirror diameter: 12 in (0.3 m)
  • Secondary mirror weight: 27.4 lb (12.3 kg)

Hubble has been serviced five times. These are the highlights of each servicing mission: 

  • Servicing Mission 1 - STS-61, December 1993: A corrective optics package was installed, and the Wide Field Planetary Camera was replaced with the Wide Field and Planetary Camera 2 (including an internal optical correction system.) The computers were upgraded. The astronauts also replaced solar arrays, gyroscopes, magnetometers, computers and other equipment. 
  • Servicing Mission 2 - STS-82, February 1997: Among other tasks, astronauts installed the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), replacing the GHRS and the FOS. An unexpected problem with NICMOS shortened its expected lifespan to only 2 years, less than half of initial projections.
  • Servicing Mission 3A - STS-103, December 1999: The third servicing mission was divided into two parts after three of the six gyroscopes (pointing devices) failed on Hubble. Just a few weeks before 3A lifted off, a fourth gyroscope failed and left the telescope unable to point in the right direction for observations. 3A replaced all the gyroscopes, a fine guidance sensor and the computer, among other tasks. The mission put Hubble back in service shortly after the repairs were completed.
  • Servicing Mission 3B - STS-109, March 2002: This mission installed the Advanced Camera for Surveys (replacing the FOC), repaired NICMOS and replaced the solar arrays.
  • Servicing Mission 4: Servicing Mission 4 - STS-125, May 2009: This mission was at first scheduled for February 2005, but NASA canceled it after the Columbia shuttle was damaged during launch and broke up during re-entry in 2003, killing seven astronauts. Hubble is in a different orbit than the International Space Station. Should a shuttle be damaged upon liftoff, there was no safe haven for astronauts to retreat to in case of emergency. However, following outcry from Congress, the scientific community and the public, the Hubble mission was reinstated and scheduled for 2008. When one of Hubble's data-handling units failed, the mission was pushed back to 2009 to include a replacement part for that, too. The astronauts on Mission 4 repaired or replaced several systems and installed two new instruments: Wide Field Camera 3 and the Cosmic Origins Spectrograph.

Hubble's elevated perspective and advanced optics allow it to peer farther away than previous ground-based optics are able to see. Because light takes time to travel long distances, the range of the HST makes it function similar to a time machine; the light it views from remote objects only reveals how that object appeared when the light left it, not how it appears today. Thus when we look at the Andromeda galaxy, 2.5 million light-years from Earth, we see it as it was 2.5 million years ago.

This image shows primordial dwarf galaxy candidates circled in green. Three enlargements at right show several dwarf objects that are at the limits of Hubble's present instrument capabilities. The Hubble UDF is a small region of sky in the direction of the southern constellation Fornax. The faintest objects are less than one four-billionth the brightness of stars that can be seen with the naked eye.
This image shows primordial dwarf galaxy candidates circled in green. Three enlargements at right show several dwarf objects that are at the limits of Hubble's present instrument capabilities. The Hubble UDF is a small region of sky in the direction of the southern constellation Fornax. The faintest objects are less than one four-billionth the brightness of stars that can be seen with the naked eye.
Credit: NASA, ESA, R. Windhorst (Arizona State University) and H. Yan (Spitzer Science Center, Caltech)

And with Hubble, distant objects are revealed that otherwise can't be seen at all.

When astronomers pointed the HST to a seemingly empty patch of sky in Ursa Major in 1995, for instance, they captured an image of over 3,000 galaxies too distant to be detected by other telescopes. (This was later called the Hubble Deep Field). Some of the galaxies were so young, they had not yet begun serious star formation. Other deep field observations in the same area were performed, peering deeper into space each time. These were called the Hubble Ultra-Deep Field (released in 2004) and the Hubble eXtreme Deep Field (released in 2012). 

In addition to gazing at the early universe, Hubble also helped astronomers gauge how much time had passed since the Big Bang. By measuring a special kind of pulsing star known as a Cepheid variable, they were able to narrow down the age of the universe from its pre-HST range of 10 to 20 billion years to a more precise 13.7 billion years.

Hubble also examines individual stars in various stages of their evolution – from the clouds of dust that form infant stars to the corpses of those long since detonated, and those in between. It has even been able to peer outside of our galaxy, the Milky Way, and into its neighbors, the Magellanic Clouds and Andromeda Galaxy.

More challenging to see than stars are planets orbiting other suns. Yet in 2008, Hubble captured pictures of the planet Fomalhaut b, the first time an extrasolar planet was directly imaged in visible light. But most planets are more challenging to photograph. Much of the HST's work with other planets comes through the detection of their atmosphere as they pass in front of their sun; the atmosphere filters the light from the stars, and the Hubble records the changes.

Hubble may spend much of its time peering light-years from Earth, but on occasion it takes the time to photograph the planets traveling around our sun. High resolution images taken of Jupiter, Saturn, and even Pluto can provide insights that can only be topped by planetary probes circling the planets. Images from the HST allows scientists on Earth to monitor changes in the planet's atmosphere and surface. When the comet Shoemaker-Levy crashed into the Jupiter in 1994, Hubble photographed the fatal collision. The aftermath revealed a great deal about the gas giant's atmosphere.

Further, Hubble has seen what appears to be water plumes erupting from the moon Europa, a moon of Jupiter. The telescope made an initial observation in March 2014 and then saw a follow-up candidate plume in the same location in February 2016.

In orbit for more than two decades, Hubble has provided scientists with a greater understanding of the planets, galaxy, and the whole universe. Among the Most Amazing Hubble Discoveries and research projects:

  • Creating a 3-D map of mysterious dark matter.
  • Discovering Nix and Hydra, two moons of Pluto.
  • Helping determine the rate of the universe's expansion.
  • Discovering that nearly every major galaxy is anchored by a black hole.
  • Helping refine the age of the universe.

Here are some additional highlights of Hubble's discoveries for the past five years:

Below are some of the best images taken by the Hubble [See a gallery of awesome Hubble pictures]:

The Helix Nebula, a planetary nebula in the constellation Aquarius also known as the "Eye of God."
The Helix Nebula, a planetary nebula in the constellation Aquarius also known as the "Eye of God."
Credit: NASA, ESA, and C.R. O'Dell (Vanderbilt University)

This massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.
This massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.
Credit: NASA, ESA, and F. Paresce (INAF-IASF, Bologna, Italy), R. O'Connell (University of Virginia, Charlottesville), and the Wide Field Camera 3 Science Oversight Committee

The Hubble Space Telescope has caught the most detailed view of the Crab Nebula in one of the largest images ever assembed by the space-based observatory.
The Hubble Space Telescope has caught the most detailed view of the Crab Nebula in one of the largest images ever assembed by the space-based observatory.
Credit: NASA/ESA and Jeff Hester (Arizona State University).

Hubble catches Jupiter changing its stripes. High and low elevation clouds switch places, changing their shape and color as they do so.
Hubble catches Jupiter changing its stripes. High and low elevation clouds switch places, changing their shape and color as they do so.
Credit: NASA, ESA, A. Simon-Miller (NASA Goddard Space Flight Center), A. Sánchez-Lavega, R. Hueso, and S. Pérez-Hoyos (University of the Basque Country), E. García-Melendo (Esteve Duran Observatory Foundation, Spain), and G. Orton (Jet Propulsion Laboratory)

Hubble catches an instantaneous glimpse of many hundreds of thousands of stars moving about in the globular cluster M13.
Hubble catches an instantaneous glimpse of many hundreds of thousands of stars moving about in the globular cluster M13.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Saturn's Rings in Ultraviolet – A new look at some of the most well-known rings in the solar system. Credit: NASA and E. Karkoschka (University of Arizona)

Hubble Ultra Deep Field – Staring at a patch of dark sky, the HST turned up over 10,000 early galaxies unseen from the surface of Earth.. Credit: NASA, ESA, R. Windhorst (Arizona State University) and H. Yan (Spitzer Science Center, Caltech)

When Galaxies Collide – Two colliding galaxies produced a long-tailed, ring-shaped galaxy. Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

A Moon of Uranus – The HST captures an eclipse as the moon, Ariel, passes in front of the sun. Credit: NASA, ESA, L. Sromovsky (University of Wisconsin, Madison), H. Hammel (Space Science Institute), and K. Rages (SETI)

Hubble captures images of dust storms on the red planet at the polar caps. Credit: NASA, James Bell (Cornell Univ.), Michael Wolff (Space Science Inst.), and The Hubble Heritage Team (STScI/AURA)

Butterfly Emerges From Stellar Death – A dying star ejecting dust and gas has created a beautiful planetary nebula. Credit: NASA, ESA, and the Hubble SM4 ERO Team

Cosmic Pearls From Supersonic Shockwave – Shock waves unleashed from a 1987 supernova are now colliding with the dust and gas around the star, heating the ring and causing it to glow. Credit: NASA, P. Challis, R. Kirshner (Harvard-Smithsonian Center for Astrophysics) and B. Sugerman (STScI)

Galactic Gas Bubbles – A bubble of gas in the center of the galaxy NGC 3079 rises above the flattened disk. Credits: NASA, Gerald Cecil (University of North Carolina), Sylvain Veilleux (University of Maryland), Joss Bland-Hawthorn (Anglo- Australian Observatory), and Alex Filippenko (University of California at Berkeley).

Eta Carinae – The Dumbel Explosion – Dust and gas exploding on both sides of the star, Eta Carinae, are shown in remarkable detail. Structures only 10 billion miles across can be observed despite the stars great distance. Credit: Jon Morse (University of Colorado), and NASA

The Ring Nebulae – A dying star shucked off the dust and gas to create the most famous planetary nebulae. The HST revealed dark clumps of material embedded in the edges of the gas ring, while the dying star hides in the center. Credit: The Hubble Heritage Team (AURA/STScI/NASA)

Preparing for the Trip to Vesta – Images taken by the HST helped astronomers and engineers plan for NASA's Dawn Mission to the asteroid Vesta and the protoplanet Ceres. Credits for Vesta: NASA; ESA; L. McFadden and J.Y. Li (University of Maryland, College Park); M. Mutchler and Z. Levay (Space Telescope Science Institute, Baltimore); P. Thomas (Cornell University); J. Parker and E.F. Young (Southwest Research Institute); and C.T. Russell and B. Schmidt (University of California, Los Angeles). Credits for Ceres: NASA; ESA; J. Parker (Southwest Research Institute); P. Thomas (Cornell University); L. McFadden (University of Maryland, College Park); and M. Mutchler and Z. Levay (Space Telescope Science Institute)

A Stream of Sub-atomic Particles – Electrons and other sub-atomic particles stream from a black hole in the center of the galaxy M87. Credit: NASA and The Hubble Heritage Team (STScI/AURA)

Shoemaker-Levy Bruises Jupiter – When the comet Shoemaker-Levy bombarded Jupiter in 1994, it left its mark on the planet. Credit: Hubble Comet Team and NASA

Additional reporting by Elizabeth Howell, Space.com contributor