Space geekout time! Have a look at this amazing photo made by the European probe Mars Express
Image is cropped. Click for full version
We are looking at Phobos (the Greek God of fear), the larger of the two moons of Mars against the limb of the planet Mars itself. There are at least two reasons why I find this photo fascinating.
First, it shows quite well how dark Phobos is. In fact many little bodies out in space (like asteroids) are dark as coal. But every time we get pictures of them, they appear grey, right? Take a look at this photo of Phobos for example. The reason is that they are often shot against the blackness of space. So the cameras are often set for over-exposure in order to see anything at all. The colors are often even greatly exaggerated in order to identify scientifically interesting features. Space photos show rarely what a human would see if they went there. The photo above is a very nice exception. It gives a much better idea of how those objects actually look like.
The second reason is because it shows how tiny Phobos is. When we think of moons we tend to imagine our own Moon. What many people don’t realize that our Moon is one of the largest Moons in the Solar System. There are a few slightly larger ones, but then our Moon is definitely the largest in relation to it’s parent body. Phobos is a good example for the vast majority of the moons out there. They are often just tiny pebbles… I mean relative to our Moon. Phobos is still 22km across, 2,5 times the height of Mount Everest. One hell of a pebble.
And it’s generally a very interesting moon. I have already written about the mysterious streaks on it’s surface. It’s origin is not really well understood either. Some think it may be a captured asteroid. However it has a very tight orbit around Mars which kinda contradicts this theory. The orbit is actually so close that Phobos will someday either fall to the surface or burst into tiny pieces due to the tidal forces. But don’t rush to mark the date, it may take around 11 million years.
Finally, there is also a mysterious huge monolith on it’s surface. I am not kidding.
The kicker is that there is a Russian mission to Phobos scheduled to launch this year. It will land on Phobos, take some samples and fly all the way back to Earth. Hopefully it will solve some of the mysteries in the process… and find even more new ones! I told you the Solar System is hardcore.
