Hubble Telescope at 20: NASA Astronomers' Top Photos

Hubble Telescope's Cultural Impact
Image courtesy NASA
Twenty years ago Saturday, the NASA space shuttle Discovery launched from Florida carrying what would become one of the most iconic instruments in astronomy: the Hubble telescope.
(See a National Geographic magazine time line of the Hubble telescope's greatest hits.)
Since then Hubble has suffered a key mirror malfunction and shuttle tragedies that put critical repair and upgrade missions at risk. Even so, NASA mission managers say Hubble has exceeded all scientific expectations during its two decades in orbit. (See pictures of Hubble's hottest science discoveries.)

Thanks to the space telescope's jaw-dropping images—like this picture of the stellar nursery known as NGC 602 released in January 2007—"Hubble has done what maybe no other scientific experiment before it had done," said astrophysicist Mario Livio.
"Hubble has gotten people interested in space and science related to the universe who never had any interest in this kind of science before. Hubble images have become a part of our culture," added Livio, of the Space Telescope Science Institute in Baltimore, Hubble's science and operations center.

To commemorate Hubble's 20th anniversary, NASA has released Hubble: A Journey Through Space and Time, a book of images—including the pictures presented here—that best highlight the telescope's scientific and societal impacts, according to NASA astronomers.

—Brian Handwerk
Published April 24, 2010
Hubble Telescope's Cosmic Eskimo
Image courtesy NASA
Using a ground-based telescope, astronomer and telescope maker William Herschel was the first to spot this nebula. Even from Earth's surface, the so-called Eskimo nebula—which sits about 5,000 light-years away—resembles a human face wearing a furry parka.
The Hubble telescope, however, saw details Herschel could never have dreamed of when it took a picture of the nebula shortly after a December 1999 servicing mission.

Hubble revealed a central, dying star blowing out gasses and materials at high speed. The doomed stellar "face" is surrounded by a disk strewn with cometlike objects, which leave behind tails as they streak away from the sunlike star. (Read about the new Imax movie Hubble 3D.)
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Sunset on Hubble Telescope Mission
Image courtesy NASA
A sunset bathes the space shuttle Discovery in a rosy glow during the second mission to service the Hubble telescope in February 1997.

That mission outfitted the telescope with new infrared-sensitive equipment so Hubble could see the most distant galaxies in the universe. Light from these objects gets stretched into longer, redder wavelengths by the universe's accelerated expansion.

During Hubble's 20 years in space, shuttle crews have visited the orbiter five times to make repairs and upgrade the instrument's capabilities. The final scheduled service mission was completed in 2009. (See Hubble's first pictures following the final servicing mission and read "Hubble Renewed," from National Geographic magazine.)
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Hubble Telescope Reveals a Scorpion
Image courtesy NASA
Like a cosmic chandelier, the dazzling lights of the star cluster Pismis 24 hang over the dusty clouds of NGC 6357, a nebula about 8,000 light-years from Earth in the constellation Scorpius. (See a more recent view of Pismis 24.)
The Hubble telescope's high-resolution picture, taken in 2006, allowed astronomers to zoom in on the brightest star in the cluster, which had appeared to be 200 to 300 times the mass of the sun in images captured by older telescopes. Such a heavyweight would have broken the theoretical limit for stellar mass—no single star should be able to get bigger than 150 times the mass of the sun without becoming too unstable to survive.
Hubble helped theorists breathe easier: The picture showed that the massive star is in fact two stars in a tight binary orbit. Each star is about a hundred times the sun's mass.
(See recent Hubble telescope images from National Geographic magazine.)
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Hubble Telescope Sees Sword's Details
Image courtesy NASA
Stargazers see this nebula—a massive cloud of dust and gas—in the familiar constellation Orion, where it appears to the naked eye as the brightest "star" in the hunter's sword.

But the orbiting Hubble telescope gets the full details, not only due to magnification, but also because the telescope can "see" wavelengths invisible to human eyes. Released in 2006, this picture of the Orion Nebula is a combination of visible and ultraviolet light from Hubble, along with infrared data from the Spitzer Space Telescope.

The composite image shows hundreds of young stars, which are emitting ultraviolet light and streams of charged particles called stellar wind. The particle streams sculpt the dusty cloud into its dramatic swirling shape.
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Hubble Telescope Repair
Image courtesy NASA
Astronaut F. Story Musgrave hangs above the world from the robotic arm of the space shuttle Endeavour as he prepares to place protective covers on the Hubble telescope's magnetometers during the space telescope's first servicing mission in 1993.

Hubble's early years were marred by an unexpected glitch: The telescope's primary mirror wasn't shaped right, and the orbiter was returning blurred images no better than what ground telescopes were producing at the time.
The first servicing mission installed two instruments to correct the problem, the Wide Field and Planetary Camera 2 (WFPC2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR).
Endeavour's 11-day 1993 mission, which included five spacewalks, was a double success—the upgraded Hubble returned unprecedented pictures of the universe, and the crew proved that instrument repairs could be performed in orbit.

The final servicing mission to Hubble last year installed new equipment that replaced WFPC2 and COSTAR, which were brought back to Earth. (Find out how to see WFPC2 and COSTAR at the National Air and Space Museum.)
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Hubble Telescope Spies Eagle
Image courtesy NASA
A Hubble teslescope picture released in 2005 shows a towering column of dense gas in the Eagle Nebula, where radiation and winds from young stars help to sculpt such spectacular features.

"The intense radiation from these stars and the charged particles that they emit erode the gas and dust in the immediate vicinity," said the Space Telescope Science Institute's Livio. "Left behind are the densest parts in the form of columns—kind of like what you'd see in Monument Valley (see picture) here on Earth," due to our planet's weathering process.
The Eagle Nebula, some 7,000 light-years away, is also home to the Pillars of Creation, similar gas columns that were immortalized by an iconic 1995 Hubble picture. The pillars are visible only because of the time it takes light from the nebula to reach Earth—they were likely destroyed some 6,000 years ago.
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010
Hubble Telescope's "Sweet 16" Shot
Image courtesy NASA
For the Hubble telescope's "sweet 16" in 2006, NASA released the sharpest wide-angle view yet of M82, aka the Cigar galaxy.
Known as a starburst galaxy, M82 is a cosmic nursery in which stars are being created ten times faster than in our own Milky Way. Each of the starlike objects seen in the image is actually a cluster of up to a million stars. These clusters produce strong streams of charged particles, which compress the gases around them and begin the star creation process anew.
The idea of an orbiting telescope free from Earth's atmospheric distortions originated in the 1920s. Many decades later, Hubble has helped answer many longstanding questions about the numerous objects seen in the night sky.
Other discoveries were unexpected: Because of the time it takes light to travel, "very deep observations of the universe now reveal galaxies to us as they looked when the universe was only 600 million years old," said the Space Telescope Science Institute's Livio. "Today it's 13.75 billion years old. Nobody thought that we would see galaxies [of that age].

"Nobody anticipated that Hubble would discover the host galaxies of gamma ray bursts or the atmospheric composition of extrasolar planets," Livio added. "Yet Hubble did all these things and more."
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.
Published April 24, 2010