Shortly after Hubble was deployed in 1990, the observatory's primary mirror was discovered to have an aberration that affected the clarity of the telescope's early images. Astronauts repaired Hubble in December 1993. Including that trip, there have been five astronaut servicing missions to Hubble.
This photograph of NASA's Hubble Space Telescope was taken on the second servicing mission to the observatory in 1997. Credit: NASA
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From the dawn of humankind to a mere 400 years ago, all that we knew about our universe came through observations with the naked eye. Then Galileo turned his telescope toward the heavens in 1610. The world was in for an awakening.
Saturn, we learned, had rings. Jupiter had moons. That nebulous patch across the center of the sky called the Milky Way was not a cloud but a collection of countless stars. Within but a few years, our notion of the natural world would be forever changed. A scientific and societal revolution quickly ensued.
In the centuries that followed, telescopes grew in size and complexity and, of course, power. They were placed far from city lights and as far above the haze of the atmosphere as possible. Edwin Hubble, for whom the Hubble Telescope is named, used the largest telescope of his day in the 1920s at the Mt. Wilson Observatory near Pasadena, Calif., to discover galaxies beyond our own.
Hubble, the observatory, is the first major optical telescope to be placed in space, the ultimate mountaintop. Above the distortion of the atmosphere, far far above rain clouds and light pollution, Hubble has an unobstructed view of the universe. Scientists have used Hubble to observe the most distant stars and galaxies as well as the planets in our solar system.
Hubble's launch and deployment in April 1990 marked the most significant advance in astronomy since Galileo's telescope. Our view of the universe and our place within it has never been the same.
• NASA's Hubble Space Telescope was launched April 24, 1990 on the space shuttle Discovery from Kennedy Space Station.
• Hubble has made more than 1 million observations since its mission began in 1990.
• Astronomers using Hubble data have published more than 12,700 scientific papers, making it one of the most productive scientific instruments ever built.
• Hubble does not travel to stars, planets or galaxies. It takes pictures of them as it whirls around Earth at 17,500 mph.
• Hubble has circled Earth and gone more than 3 billion miles along a circular low earth orbit of 340 miles altitude.
• Hubble has no thrusters. To change angles, it uses Newton’s third law by spinning its wheels in the opposite direction. It turns at about the speed of a minute hand on a clock, taking 15 minutes to turn 90 degrees.
• It’s has the accuracy of .007 arc seconds, which is like being able to shine a laser beam on a dime 200 miles away.
• Outside the haze of our atmosphere, it can see astronomical objects with an angular size of 0.05 arc seconds, which is like seeing a pair of fireflies in Tokyo from your home in Maryland.
• Hubble has peered back into the very distant past, to locations more than 13.4 billion light years from Earth.
• Hubble generates about 10 Terabytes of new data per year.
• Hubble weighs 24,500 pounds -- as much as two full-grown elephants.
• Hubble's primary mirror is 2.4 meters (7 feet, 10.5 inches) across.
• Hubble is 13.3 meters (43.5 feet) long -- the length of a large school bus.
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For Hubble achievements, please see:
History of Hubble
A detailed look at the Hubble Space Telescope from idea to conception to blast off into space. Learn all about the project from its infancy to the maturing telescope it was when launched in 1990.
Explore the development of the Hubble Space Telescope and learn about the important dates in history that has contributed to the success of the telescope.
Thanks in part to the Hubble Space Telescope, we know the universe is 13.7 billion years old.
Nearly all galaxies may harbor supermassive black holes.
The Hubble Space Telescope has helped scientists determine the process of how planets are born.
The Hubble Space Telescope detected the first organic molecule discovered on a planet outside our solar system.
The Hubble Space Telescope detected a distant supernova that suggests the universe only recently began speeding up.
Hubble found four moons around dwarf planet Pluto.