This false-color composite image of the Stephan’s Quintet galaxy cluster clearly shows one of the largest shock waves ever seen (green arc). The wave was produced by one galaxy falling toward another at speeds of more than one million miles per hour. The image is made up of data from NASA's Spitzer Space Telescope and a ground-based telescope in Spain.
Four of the five galaxies in this picture are involved in a violent collision, which has already stripped most of the hydrogen gas from the interiors of the galaxies. The centers of the galaxies appear as bright yellow-pink knots inside a blue haze of stars, and the galaxy producing all the turmoil, NGC7318b, is the left of two small bright regions in the middle right of the image. One galaxy, the large spiral at the bottom left of the image, is a foreground object and is not associated with the cluster.
The titanic shock wave, larger than our own Milky Way galaxy, was detected by the ground-based telescope using visible-light wavelengths. It consists of hot hydrogen gas. As NGC7318b collides with gas spread throughout the cluster, atoms of hydrogen are heated in the shock wave, producing the green glow.
Stephan's Quintet is located 300 million light-years away in the Pegasus constellation.
This panoramic view of the eye of Hurricane Emily was shot by the crew of the International Space Station while they passed over the southern Gulf of Mexico looking eastward toward the rising moon. This July 16, 2005 image shows the eye of the hurricane, which appears as a depression in the cloud deck, stretches out to the horizon and fades into the limb (the bright blue cross-section) of the Earth’s atmosphere. At the time this image was taken, Emily was a strengthening Category 4 hurricane. With the formation of Hurricane Emily, 2005 became the first season in which there were two Category 4 storms before the end of July.
The Phoenix Mission, slated for launch in August 2007, is the first project in NASA's program of Mars Scout missions. The Phoenix Lander is currently housed in a 100,000-class clean room at Lockheed Martin Space Systems' facilities near Denver, Colo. The Phoenix team continues to make specific modifications and prepare for assembly, test and launch operations to get underway in spring 2006.