APOD 4.1

For this week's APOD, I chose the picture called MESSENGER at Mercury.  It is an image taken on March 17 by the MESSENGER Spacecraft.  The picture shows some of Mercury's many craters and terrains.


The MESSENGER Spacecraft was the first spacecraft to go into orbit around Mercury, which is the innermost planet in our solar system.  Although Mercury will offer good views this month due to this planet wandering away from the Sun in the Earth's sky, it is still better seen from spacecrafts in orbit around it.  The picture shown is the first image of the planet in color since the spacecraft entered the orbit.  In comparison to the Moon, Mercury is bigger, more dense, and has about twice the surface gravity.  But even with these differences, the two tend to look very similar when first examined.  The terrain areas in the photograph are almost a shade of light blue and brown.  Many craters are seen within these terrains as well.   Towards the top of the photo, one can point out long streaks of material hitting the surface.  In the center of the rays in the crater Debussy, which happens to be 80 kilometers in diameter. The rays contain impact ejecta and secondary craters.  The part of the Debussy shown here is only a portion of the whole thing. At the other bottom end of the image of Mercury, terrain is extended to it's south pole, with a region that has never before been captured from space.