A look by Messenger at the crater called Verdi on Mercury. The crater is 90 miles (145 km) in diameter. Click for larger. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The Messenger spacecraft has entered one of the “hot periods” in its mission.

Mercury is quite interesting for a number of reasons and one of them is that it has the most eccentric orbit of any in the solar system.  The distance between Mercury and the Sun varies from 43.7 million miles to 28.8 million miles over the 88 day orbit.  The closer Mercury is to the Sun it stands to reason the hotter the temperatures the planet and the orbiting spacecraft get.  Just to be clear, the distance the Earth varies in its orbit is not enough to make a difference in our temperatures and it is the tilt that is responsible for the seasons.

Anyways, Mercury and Messenger reached their closest point to the Sun just a few days ago.  Mercury does have a sunshade and the temperatures on that shade device are 350^oC or how about 660^oF!  The spacecraft spends about an hour on the sunlit side and then travels about the same time on the dark side of the planet where temps can plunge to ^-172^oC or ^-279^oF.  It is quite a feat to keep Messenger going.

Tomorrow hopefully we will get some early science data from Messenger at a news conference.  Fingers crossed.