In total coherency with my last post, I found this on APOD (Astronomy Picture of the Day). The relentless tidal forces of Mars will someday shatter its moon Phobos. It orbits ‘too close’, only about 5800 kilometers above the surface while our moon is about 400,000 kilometers away. Mars was named after the Roman god of war and the moons were named after Mars’ Greek equivalent, Ares’ two sons Phobos and Deimos, Phobos meaning fear and Deimos meaning dread. Overall, a very dark and warlike mythology surrounds these neighbors.
Phobos is closer to its planet than any other known planetary moon. Because its orbit is faster than Mars itself rotates, it rises in the west and sets in the east and it does so twice each day. Phobos is less than 7 miles in diameter and from its surface Mars would appear to take up a quarter of the width of a celestial hemisphere, huge.
There was an interesting theory by a Russian scientist in the mid 50’s that Phobos was a hollow body. More modern measurements show it to consist of 30% (+ or – 5%) voids, but these are of a very small size. I get a kick out of pretending it has a large hollow interior and the implications that could mean for humans on earth. Unfortunately, I think it would cause more fear (so an appropriate name) than wonder.
This picture from the Mars Reconnaissance Orbiter has an incredible resolution of 7 meters per pixel. Here is a link to this picture and explanation: