The Why Files The Why Files --

Astronomy in Orbit

Hubble Space Telescope: Sweet 15
Hubble, the observatory that could -- and still can -- has celebrated 15 years in orbit. The big 'scope produced the greatest scientific successes of the space program. It's seen stars being born, stars dying, galaxies colliding, and planetary disks forming.

Hubble was followed by three other "great observatories" in space. Each of these big, expensive gadgets grabs a specific type of light, which contains a unique type of information about the ancient, distant universe.

Space telescope floats in black expanseAfter the March, 2002, repair trip, Hubble floats free to continue its voyage of discovery. Photo: Hubble

Some bureaucrats think the ideal honorific for Hubble is to retire the trusty looking glass. We'd prefer to observe the 15th anniversary by viewing some of Hubble's recent triumphs.

Not to discriminate against other parts of the electromagnetic spectrum, we'll also offer a round-up of images from three other great observatories: Spitzer (infrared) and Chandra (X-ray).

Patient photons
Have you ever stared into darkest space and wondered what was beyond your vision? A year and a half ago, Hubble peered at a dark patch of sky for 11 days, and came up with a view of almost 10,000 galaxies -- in the deepest-ever visible-light view of the sky. Some of the photons collected for this image had been schlepping across the universe for more than 12 billion years before they slammed into Hubble's mirror and got redirected to its the Advanced Camera for Surveys, which was installed during the 2002 service mission -- one argument for continuing to repair NASA's best science machine. The camera sees several times further than the instrument it replaced.

Photograph of the night sky, galaxies noticeable
Hubble's epic deep-field image, covering a field of view one-tenth the moon's diameter. Click here for a larger, 496 KB image. Photo:Hubble site. Read a detailed description of this masterpiece: Hubble site

Because the universe is expanding, more distant objects are receding faster from Earth; the movement "stretches" their light and makes it redder. The deep-field image contains about 100 red galaxies, among the most distant ones ever seen, relics of the universe as it appeared just 800 million years after the Big Bang. The nearer galaxies are larger, brighter and younger, with clear-cut spiral or elliptical shape.

Hubble's 11-day snapshot was exciting enough to coax the poets at NASA out of hiding, and they described "a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. These oddball galaxies chronicle a period when the universe was younger and more chaotic. Order and structure were just beginning to emerge."

See the Hubble slide show.

Put yourself into the infrared zone.


Megan Anderson, project assistant; Terry Devitt, editor; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

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