Newly released ESA images of Holmberg II and Markarian 509 reveal these galaxies' inner workings. Both have stories unlike that of our home galaxy, the Milky Way.
Far from being dead, the exosphere of Mercury is dynamic and continually renewing. This gives astronomers clues about the planet's surface and environment.
Solar wind sandblasts Mercury because its weak magnetic field provides little protection from the fierce solar wind, a squall of charged particles from the sun.
A geomagnetic storm is in progress. If it's nighttime, and you're at a high latitude, go outside and look for auroras! And quit worrying, you. Just enjoy.
UARS penetrated the atmosphere over the Pacific. No debris has been found. There are no reports of injury or property damage. Hoax videos are circulating.
All of launch dates are tentative, but are a welcome step after concerns that launches would cease due to an unmanned Soyuz crash over Siberia on August 24.