here it is, thing I wanted to do a long time: first post about first planet of our lonely Solar System.
Mercury, it is the first and closest planet to Sun. It means one simple thing, it is freaking hot.. but not always.. actually it is not that hot but you would die there, that´s for sure.
The name is same as for Roman god of messengers and travelers. It has strangest orbit of all planets, most elliptical since when you look on other planet´s it looks like circle. Here Mercury is moved by great distance: in Perihelion (close to Sun) it is 0,307 AU away but in Aphelion 0,467 AU. Also orbit is declined by 7° from Earth´s orbit.
This huge piece of rock has really weak exosphere and also really weak magnetosphere. Magnetosphere is probably so weak because axis of Mercury is only 0,1° declined while our is 23° or so… There is no stable atmosphere because Mercury can not hold it from solar winds.
Solar winds are so strong here that they are probably eroding planet´s surface.
Even that there are extreme temperatures so one would except that all water would evaporate but in cracks on poles there are actually tons of tons of water ice!
On the side turned towards Sun can be over 450°C while on the other there is below -170°.
Mercury is not geologically active. It´s year lasts 88 days and day 58 Earth days. This and elliptical orbit create really strange event. When it is about midday on Mercury, Sun stops and for few days it goes backwards and then again it goes in the right way.
Most craters are named by artists and one of them is named Tolkien. There is also one of the biggest craters in whole solar system with 1600 kilometers across and it is called Caloris Basin.
First satellite which mapped the surface was Mariner 10 but much better data was send by Messenger.