- 9:56 pm - Fri, Jul 26, 2013
- 398 notes
The planet where it rains rocks
The close proximity of COROT-7b to its star (just 1.6 million miles) keeps it gravitationally locked in place just as the moon is to the Earth, meaning the same side of always faces the star. As such, it stays very, very hot there (about 4,220 degrees Fahrenheit). That kind of heat vaporizes rocks, and that’s exactly what happens on COROT-7b. Using computer modeling, the team at Washington ran through four different scenarios with four different starting compositions (since the exact makeup of the planet is unknown) with the same result each time.
Just as water vaporizes in our atmosphere only to condense at higher, cooler altitudes and fall back to the Earth as rain, so do the sodium, potassium, silicon monoxide, magnesium, aluminum, calcium and iron of COROT-7b. When they condense, however, they condense into rock clouds that rain little pebbles of different types of rocks. What’s more, the type of rock is dependent on altitude. The atmosphere gets colder the higher up the rock vapor goes. Since each rock or mineral has a different boiling point, the materials with the highest boiling points will condense out at lower altitudes, while the ones with lower boiling points can rise higher as vapor before condensing back into rocks.
Image credit: Ron Miller