APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
A Sailing Stone in Death Valley
Explanation: How did this big rock end up on this strange terrain? One of the more unusual places here on Earth occurs inside Death Valley , California , USA . There a dried lakebed named Racetrack Playa exists that is almost perfectly flat, with the odd exception of some very large stones, one of which is pictured above . Now the flatness and texture of large playa like Racetrack are fascinating but not scientifically puzzling -- they are caused by mud flowing, drying, and cracking after a heavy rain. Only recently, however, has a viable scientific hypothesis been given to explain how 300-kilogram sailing stones ended up near the middle of such a large flat surface. Unfortunately, as frequently happens in science, a seemingly surreal problem ends up having a relatively mundane solution. It turns out that high winds after a rain can push even heavy rocks across a temporarily slick lakebed.
| Date | February 22, 2012 |
|---|---|
| Credit | Image Credit: Nathan Alexander , Wikipedia |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |



