The action is all in the arms - the spiral arms, that is. That’s where a spiral galaxy’s stars are born. It’s also where the most massive stars explode as supernovae, squeezing clouds of gas and dust to give birth to even more stars.
Those arms have been one of the main targets of GALEX - the Galaxy Evolution Explorer. The small space telescope was launched 10 years ago today.
GALEX looks at the universe in ultraviolet light. Earth’s atmosphere blocks most ultraviolet energy, so the only way to get a clear look at the ultraviolet universe is with a space telescope.
Ultraviolet energy is produced by some of the hottest objects in the universe, including massive young stars. To the eye alone, these stars shine blue-white. But they actually produce far more ultraviolet light than visible light - hence the need for a space telescope to study them.
GALEX has mapped the star-forming regions of many galaxies, providing new insights into how all stars are born, and how the most massive stars die. It’s also produced a catalog of ultraviolet-producing galaxies across the entire sky - something that had never been done before.
GALEX is still going, although it has a new operator. The spacecraft was built and launched by NASA. But last year, NASA “loaned” the satellite to Caltech. Using private funding, it’s continuing to operate GALEX well after the planned end of its mission - allowing astronomers to keep an eye on where the action is.
Script by Damond Benningfield, Copyright 2013