NASA's Galaxy Evolution Explorer has beamed back revealing images of hundreds of galaxies to expectant astronomers, providing the first batch of data on star formation that they had hoped for.

This three-color image of galaxy M101 was taken by GALEX on June 20, 2003. The far ultraviolet emissions are shown in blue, the near ultraviolet emissions are green, and the red emissions, which were taken from NASA's Digital Sky Survey, represent visible light. This image combines short, medium, and long "exposure" pictures to best display the evolution of star formation in a spiral galaxy. Credit: NASA/JPL/Caltech

The recent ultraviolet color images from the orbiting space telescope were taken between June 7 and June 23, 2003 and are available online at http://www.galex.caltech.edu.

"The images clearly show active star formation in nearby galaxies, and large numbers of distant ultraviolet galaxies undergoing starbursts," said Dr. Christopher Martin, the mission's principal investigator and an astrophysics professor at the California Institute of Technology in Pasadena, which leads the mission. "This demonstrates that the Galaxy Evolution Explorer will be a powerful tool for studying star formation in galaxies near and far."

"These stunning images provide us with valuable information needed to advance our knowledge of how galaxies, like our own Milky Way, evolve and transform," said Dr. James Fanson, Galaxy Evolution Explorer project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Pictures of the ultraviolet sky reveal objects we could never have seen with visible light alone."

The Galaxy Evolution Explorer launched on April 28, 2003. Its goal is to map the celestial sky in the ultraviolet and determine the history of star formation in the universe over the last 10 billion years.

GALEX took this image of the spiral galaxy Messier 51 on June 19 and 20, 2003. Messier 51 is located 27 million light-years from Earth. Due to a lack of star formation, the companion galaxy in the top of the picture is barely visible as a near ultraviolet object. Credit: NASA/JPL/Caltech

From its orbit high above Earth, the spacecraft will sweep the skies for up to 28 months using state-of-the-art ultraviolet detectors. Looking in the ultraviolet singles out galaxies dominated by young, hot, short-lived stars that give off a great deal energy at that wavelength. These galaxies are actively creating stars, therefore providing a window into the history and causes of galactic star formation.

In addition to leading the mission, Caltech is also responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of Caltech, manages the mission and led the science instrument development. The mission is part of NASA's Explorers Program, managed by the Goddard Space Flight Center, Greenbelt, Md. The mission's international partners are France and South Korea.