Galaxy Evolution Explorer

~Here's a science satellite I wasn't aware of: NASA's Galaxy Evolution Explorer (GALEX), which has been orbiting Earth for over five years now. It's photographed millions of galaxies, adding information on the subject of how stars form and galaxies change over billions of years.

Originally planned as a 29-month mission, the life of GALEX has been extended thanks to its remarkable returns. One of the primary project goals is to complete a comprehensive extra-galactic ultraviolet survey, to map all major ultraviolet sources of energy in the universe. Quite a challenge, but it will give humanity an understanding of how galaxies are forming--right now--in the far reaches of space, which will help us better understand the stellar evolution of the Milky Way.

For example, it is suspected that most galaxies begin as spirals, and become elliptical galaxies over time. This is supported by the fact that elliptical galaxies tend to have more red stars, which are older than blue stars and yellow stars like the sun. Further supporting this hypothesis are images taken by GALEX of "transitional" (teenage?) galaxies, which are something between spiral and elliptical forms. Before GALEX, there were few images of these transitional galaxies for astronomers to study, but the satellite has been able to find many of them.


GALEX has also made other interesting discoveries, some of which I'd read about without realizing GALEX was behind them. For example, this was in the news a few months ago:

^ Although it looks like a comet, this image, captured by GALEX, is actually a star called Mira which hurtles through space at an astonishing 291,000 miles per hour. It's moving so fast that you can see a bow shock of gas to the right of the star, and the long trail of gas being thrown off from the movement to the left. Gas released by Mira has been excited to release ultraviolet radiation (detected by GALEX), which will cool to form material for new stars. One particular area of interest for astronomers about Mira are the "streams" labeled in the image, which are suspected to be material flowing from the polar areas of the star.

You can see and read about more of the findings from GALEX here. The satellite has enough power to last for twelve years, and I hope the mission is further extended for as long as it can be.