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> Hubble's 20th Anniversary

APR. 2010

Hubble Celebrates a Stellar Anniversary

Photo of 20th anniversary Carina Nebula image.

Hubble's 20th anniversary gift to
the public:

Zoom into a "mystic mountain" that shrouds a stellar nursery

When the Earth-orbiting Hubble Space Telescope opened its sharp "eye" on the universe 20 years ago, planets circling other stars were just a dream and no one had heard of "dark energy."

Astronomers have used Hubble to hunt for planets around other stars in the hub of our Milky Way Galaxy and to study the bright light from faraway exploding stars to collect evidence for a mysterious dark energy, which makes up most of the energy in our universe.

Hubble has helped expand our view of the cosmos, allowing us to better understand our universe and our place in it. From its lofty perch 350 miles above Earth, Hubble sees farther and sharper than any previous telescope. The observatory has imaged more than 30,000 celestial objects, snapping more than 570,000 pictures.

It's not just the scientific discoveries that have made Hubble an American icon. The telescope's breathtaking images of such cosmic beauties as Saturn and its rings, the pillars in the Eagle Nebula, and a pair of interacting galaxies called The Mice have inspired astronomers and the public.

Hubble's anniversary gift to the public

To mark the 20th anniversary of Hubble's launch and deployment into Earth orbit, NASA and the Space Telescope Science Institute are issuing another stunning image. The new photograph of a craggy fantasy mountaintop surrounded by wispy clouds captures the chaotic activity atop a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby colossal stars. Infant stars buried inside the pillar also are firing off jets of gas that can be seen streaming from towering peaks. This turbulent cosmic pillar lies within a tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation Carina.

An amazing machine

Image of Hubble upon final release

Hubble upon final release:
May 2009, after the last servicing mission it will receive

Edwin Hubble

Edwin Hubble

Hubble can take these crystal-clear views of the cosmos because it is orbiting above Earth's atmosphere, an ocean of air that smears and scatters starlight. Scientists such as Lyman Spitzer, Jr., proposed the idea of a space telescope in the 1940s. It took, however, nearly 50 years of research and planning to get a space telescope off the ground.

NASA launched Hubble on April 24, 1990 aboard the space shuttle Discovery. The observatory is named after U.S. astronomer Edwin P. Hubble who, early last century, discovered galaxies beyond our Milky Way and determined that space is expanding.

The telescope is a behemoth — the size of a school bus (43.5 feet or 13.3 meters long) and weighing more than 12 tons (11,000 kilograms). Its primary mirror is 94.5 inches wide (2.4 meters). The tubular-shaped spacecraft looks like it has wings. These wings, however, are not used to fly. They are made up of solar panels, which collect light from the Sun to help power the spacecraft's instruments

Astronauts visit an old friend

Five heroic astronaut servicing missions to Hubble have made it the longest-operating space observatory ever built. Thanks to routine maintenance and upgrades Hubble is 100 times more powerful than when it was launched.

The last astronaut journey to Hubble was May 2009. During this visit, called Servicing Mission 4, astronauts boosted Hubble's scientific power and made sure the telescope would continue to work for years to come. Astronauts installed two state-of-the-art science instruments, a wide-field camera and a spectrograph. They also added six batteries, six gyroscopes, a Fine Guidance Sensor, and repaired an aging camera and an aging spectrograph.

Hubble's top science discoveries

Helping astronomers solve many of the universe's mysteries is nothing new for Hubble. Here are some of the telescope's top science discoveries.

Galaxies from the ground up

The Zoomable Hubble Ultra-Deep Field

The zoomable Hubble Ultra Deep Field
You're the driver – take a close-up tour of one of Hubble's deepest views into the universe

Hubble's surveys of deep space showed that the universe was different long ago, providing evidence that galaxies grew over time through mergers with other galaxies to become the giant galaxies we see today. The deep views also revealed that the early universe was a fertile breeding ground for stars. Observations showed that the universe made a significant portion of its stars in a torrential firestorm of star birth that abruptly lit up the pitch-dark heavens less than a billion years after the Big Bang. Though stars continue to form in galaxies today, the star-birth rate is lower than it was a billion years ago.

An accelerating universe

By witnessing bursts of light from faraway exploding stars, Hubble provided important supporting evidence for the existence of a mysterious 'dark energy' that makes up most of the energy in the universe. This dark energy causes a repulsive force that works against gravity. Hubble observations showed that dark energy shoves galaxies away from each other at ever-increasing speeds, making the universe expand at an accelerating pace.

How old is the universe?

Hubble observations allowed astronomers to calculate a precise age for the universe. The method relied on determining the expansion rate of the universe, a value called the Hubble constant, by measuring the distances to tens of galaxies. Using the value of the Hubble constant, astronomers were able to calculate the universe's age, which is about 13.75 billion years.

Monster black holes are everywhere

Hubble probed the dense, central regions of galaxies and provided decisive evidence that supermassive black holes reside in the centers of almost all large galaxies. Although black holes cannot be observed directly, Hubble helped prove their existence by measuring the speed of stars and gas whirling around the core of galaxies. The telescope also showed that the black hole's mass is dependent on the mass of its host galaxy's central bulge of stars. The bigger the bulge of stars, the more massive the black hole. This close relationship means that black holes may have evolved with their host galaxies.

Worlds beyond our Sun

Artist's conception of closest exoplanet yet confirmed

Closest exoplanet yet confirmed:
Orbiting a Sun-like star 10.5 light-years away

At the time of Hubble's launch in 1990, astronomers had not found a single planet outside our solar system. Now there are hundreds of so-called extrasolar planets, most of them discovered by ground-based telescopes. But Hubble has made some unique contributions to the planet hunt. The telescope made the first measurements of the chemical makeup of an extrasolar planet's atmosphere, detecting carbon dioxide, methane, water, and sodium. These measurements are an important step in the search for extraterrestrial life by looking for the chemical signatures for life in a planet's atmosphere.

Hubble also made the first visible-light image of an extrasolar planet circling the star Fomalhaut. In addition, the Earth-orbiting observatory conducted the deepest survey for extrasolar planets in our Milky Way Galaxy's central bulge of stars, finding 16 potential planets.

Hubble's hall-of-fame images

Hubble's top ten favorites

Hubble's top ten favorites:
Some of the most popular Hubble images

In addition to the top-notch science discoveries, Hubble has taken a photo album's worth of memorable images, including snapshots of a gas shroud around a doomed star, a pair of colliding galaxies, and an aurora on Saturn. Here are some of the public's favorite Hubble images.

Back on Earth

In the two decades since Hubble began changing our view of the cosmos, the world, too, has undergone many changes. Here are a few of them.

During Hubble's reign, the Berlin Wall came crashing down, the Soviet Union broke apart, four men were elected president of the U.S., Hong Kong regained its sovereignty from Great Britain, and Fidel Castro resigned as the long-time president of Cuba. Jody Williams, Mikhail Gorbachev, Al Gore, and Nelson Mandela were among the Nobel Peace prize winners.

In science news, the oldest human remains, estimated to be about 4.4 million years old, were uncovered in Kenya, Africa. Footprints of a 350,000-year-old upright-walking human were spotted in Italy. The world's first artificial heart was implanted in a human. In a surprising discovery, archaeologists uncovered a 2,100-year-old melon in Japan.

While Hubble has been in space, we saw the dawn of a new millennium and a revolution in digital technology. The introduction of the World Wide Web greatly expanded the public's use of the Internet, prompting more people to buy computers for home use. Internet usage in the U.S. jumped from just a few percent to more than 70 percent. Internet search engines such as Google and Yahoo were born. Facebook, Wikipedia, and YouTube became popular Web destinations.

Ready to tackle the next cosmic mystery

Advanced technologies, new countries, and alien worlds have been born in the 20 years since Hubble was launched and deployed. With its newly installed camera, spectrograph, batteries, and gyroscopes, the Earth-orbiting observatory will continue to probe the universe's secrets for years to come.


The Star Witness

brings you "tele-scoops" from the Hubble Space Telescope