Hubble's Picture Book of the Universe
'Eye' on the universe
Hubble with its new
solar panels, 2002
In 1990, George Bush Sr. was the U.S. president,
the Nintendo video game system, Game Boy, was not on the U.S.
market, the World Wide Web did not exist for people to "surf" for
information, and NASA's Hubble Space Telescope (HST) was launched
into Earth orbit.
Astronomers had dreamed since the 1940s about launching a visible-light telescope into space. Ground-based telescopes are hampered by our Earth's atmosphere, which blurs the light from stars and makes them appear to twinkle.
That dream came true on April 24, 1990, when NASA launched Hubble aboard the space shuttle Discovery. The observatory is the first space-based visible-light telescope, orbiting about 380 miles (611 kilometers) from Earth. Hubble also sees in ultraviolet and near-infrared light. The telescope 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.
A giant 'eye' in the sky
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.
Hubble is the first of NASA's four Great Observatories, a
series of space-borne telescopes designed to view the sky over
many different wavelengths (visible, gamma rays, X-rays, and
infrared). The second was the Compton Gamma Ray Observatory,
in operation from April 1991 to June 2000. The other two Great
Observatories are the Chandra X-ray Observatory, launched in
July 1999, and the Spitzer Space Telescope, which sees in infrared
light and was sent into space in August 2003.
The Hubble telescope is helping astronomers answer many important questions about the universe and is bringing pictures of many celestial objects into sharper view.
A sampler of some 'Greatest
Some of Hubble's biggest contributions to astronomy include witnessing a shattered comet plunge into Jupiter's atmosphere, studying planets outside our solar system, and providing the deepest views of the universe in ultraviolet, visible, and near-infrared light.
Caught in the act:
A comet slams into
Jupiter's battle scars
Smudges show a comet's impact sites
Imagine setting off every atomic bomb on Earth all at once. Now imagine repeating such a titanic explosion two dozen times in a week! Unleashing such energy would destroy Earth's surface, but the giant planet Jupiter hardly flinched when it underwent such a catastrophe in 1994. Hubble provided a ringside seat to a once-in-a-millennium event when nearly two-dozen chunks of a comet smashed into Jupiter. Hubble provided dramatic images of massive explosions that sent towering mushroom-shaped fireballs of hot gas into Jupiter's sky. The doomed comet, called Shoemaker-Levy 9, had been pulled apart two years earlier by Jupiter's gravity. Each impact left temporary black marks in Jupiter's atmosphere.
Spying planets orbiting other stars
Hubble's sharp 'eye' also contributed to a greater understanding of planets
outside our solar system, called extrasolar planets. Astronomers using
ground-based telescopes to hunt for extrasolar planets have discovered
more than 100.
They needed Hubble, however, to make the first direct measurement
of the chemical makeup of the atmosphere of an extrasolar planet.
The telescope detected the elements sodium, hydrogen, carbon,
and oxygen in the planet's
The unique observation demonstrates
that Hubble and other telescopes can sample the chemical makeup
of the atmospheres of distant planets. Astronomers could use
the same technique someday to determine whether life exists
on extrasolar planets.
Glimpsing the early universe
A close-up from HUDF
Looking much farther away, Hubble provided astronomers with
a "scrapbook" full of snapshots of the early universe. The
scrapbook photographs revealed young galaxies that existed
billions of years ago, long before the earth and Sun were born.
The telescope snapped the pictures of the "deep" universe
in a series of unique observations, called the Hubble Deep
Fields, the Great Observatories Origins Deep Survey, and the
Hubble Ultra Deep Field (HUDF). The observations provided the deepest
views of the cosmos in visible, ultraviolet, and near-infrared
Through these observations, astronomers can witness how
galaxies form. By studying galaxies at different eras, astronomers
can see how galaxies change over time.
Although Hubble has taken many jaw-dropping photographs of
celestial objects, it does not always work alone. Sometimes
astronomers must look at an object through the eyes of several
telescopes that see different wavelengths of light.
in ultraviolet, visible, and near-infrared light. Other telescopes both
ground- and space-based see in wavelengths such as X-rays,
gamma rays, and infrared light. By combining Hubble with those
telescopes, astronomers get a more complete view of an object.
Looking to the future
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Hubble's top science findings
Astronomers will continue to use Hubble and other telescopes
to study the universe. Like detectives searching for clues
to a crime, astronomers are hunting for evidence to solve many
questions about our universe. Are there other worlds in space
where life exists? Where did we come from?