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Artist's concept of GALEX in orbit around Earth.

At ~2.5 million light-years away, the Andromeda galaxy is our Milky Way's largest galactic neighbor. The galaxy spans 260,000 light-years across. It took 11 different GALEX image segments stitched together to produce this view of the galaxy next door.

About Image

Artist's concept of GALEX in orbit around Earth.NASA

GALEX readies for launch.NASA (PIA04264)

At approximately 2.5 million light-years away, the Andromeda galaxy is our Milky Way's largest galactic neighbor. The entire galaxy spans 260,000 light-years across -- a distance so large, it took 11 different Galaxy Evolution Explorer image segments stitched together to produce this view of the galaxy next door.NASA/JPL–Caltech

Mission name: GALEX

Galaxy Evolution Explorer

Understanding how the galaxies were formed

Launch Date April 28, 2003
End DateJune 28, 2013
Mission TypeSpace Telescope
TargetThe Universe

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Mission Overview
The Galaxy Evolution Explorer was an orbiting space telescope designed to measure the history of star formation in the Universe by observing the Universe in ultraviolet wavelengths. In addition to paving the way for future ultraviolet missions, the space telescope allowed astronomers to uncover mysteries about the early Universe and how it evolved, as well as better characterize phenomena like black holes and dark matter. The mission was extended three times over a period of 10 years before it was decommissioned in June 2013.

Relevance to Astrobiology
Data from the GALEX mission informs a number of studies supported by the NASA Astrobiology Program. Researchers use this data to better understand the Universe and the conditions in which planetary systems form and evolve. Scientific results from GALEX are helping exoplanet researchers determine the conditions necessary for the evolution of habitable worlds. Using its ultraviolet imaging, GALEX was used to test planet detection methods based on changes in a stars activity caused by tidal or magnetic interactions with planets in orbit.

The Astrobiologists
GALEX data has contributed to studies performed by researchers supported by elements of the NASA Astrobiology Program, including the Habitable Worlds Program and NExSS.

Mission news and discoveries

Artist’s concept of the Galaxy Evolution Explorer. Its mission is to study the shape, brightness, size, and distance of galaxies across 10 billion years of cosmic history. The 19.7-inch telescope onboard sweeps the skies in search of ultraviolet-light sou

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Major mission findings

October 15, 2003The Andromeda Galaxy

The Galaxy Evolution Explorer captures the most sensitive and comprehensive image ever taken of the Andromeda galaxy. At approximately 2.5 million light-years away, the Andromeda galaxy is our Milky Way’s largest galactic neighbor. The entire galaxy spans 260,000 light-years across — a distance so large, it took 11 different Galaxy Evolution Explorer image segments stitched together to produce this view.

The GALEX spacecraft before its launch in 2003.

April 15, 2004A Giant Flare

The Galaxy Evolution Explorer captures a giant star eruption, or flare, about one million times more energetic than those from our Sun.

GALEX spotted, for the first time, dwarf galaxies forming out of nothing more than pristine gas likely leftover from the early Universe. Dwarf galaxies are relatively small collections of stars that often orbit around larger galaxies like our Milky Way.

December 15, 2004Baby Galexies

The Galaxy Evolution Explorer spots what appear to be massive “baby” galaxies in our corner of the universe, suggesting our aging universe is still alive with youth.

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Mission Facts

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This image was taken on May 21 and 22 by NASA's Galaxy Evolution Explorer. The image was made from data gathered during the missions "first light" milestone, and shows celestial objects in the constellation Hercules.

Observing HerculesHonoring Columbia

On May 28, 2003, GALEX gathered its first celestial images, observing an area of the sky in the constellation Hercules in honor of the crew of the Space Shuttle Columbia.

Mission CompleteGALEX Decommissioned

In June of 2013, GALEX was decommissioned after meeting and far exceeding its prime objectives. The spacecraft will remain in orbit for at least 65 years, then fall to Earth and burn up upon re-entering the atmosphere.

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