21 May 2008
Image credit: Inga Nielsen
Ok, apparently I am a sucker for artist’s renditions of active red dwarfs. Today’s picture is the Astronomy Picture of the Day, and shows a concept of what the surface of Gliese876d might look like. This planet is heftier than Earth and orbits closer to its star than Mercury does the sun. However, it orbits a dim red dwarf, which means that even though it is close to the star, it is in the habitable zone and liquid water might exist on the surface. Unfortunately, its close proximity to the star also may mean that it experiences some wicked tides, and may spin extremely slowly. In fact, it is possible that the planet is tidally locked to the star, just like the moon is with the Earth. This would mean that on one side of the planet it would always be daytime and the other side would always be night. Believe it or not, even a planet with one side constantly scorched and the other frozen in darkness might be habitable, but the sun would never rise or set. It would just hang there, angry in the sky.