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10

The actual density depends on the mineralogy, we don't have a crystalline iron core and silicon crust. You do have a lot of oxygen available, too when you look at the overall elementary abundance. So the abundant materials are Fayalite (${\rm Fe_2SiO_4}$), Olivine (${\rm (Fe,Mg)_2SiO_4}$), Fosterite (${\rm Mg_2SiO_4}$) etc. which make up most of the crust. ...

3

Partial answer about the retrograde motion only: Yes, the Sun has yearly retrograde motion as seen from Mercury I've written a simple script to generate the orbital motion of Mercury based on its eccentricity. I've used reduced units with $GM = a = 1$ and period $T = 2 \pi$. Mercury's rotational period is 2/3 of its orbital period. I've plotted the ...

2

Interesting question. The terms day and year become funny when you move to Mercury: Mercury is tidally locked to the Sun and has a 2:3 spin-orbit-resonance. That means that a complete day-night cycle takes two Mercury year, thus one year / orbital period around the Sun you have completely day, the other completely night). Du to this spin-orbit resonance, you ...

5

During the Messenger mission, there were (among many others) two global images of Mercury taken. One is the so called "Low Incidence Angle Mosaic" which is created from combining images taken at local noon when the Sun is high in the sky and the amount of shadows is reduced. This image is useful to see different types of surfaces. The other one is ...

2

What are those long, smooth, opposing, longitudinal smooth areas from pole to pole on Mercury? This is a partial answer because other than "they are not real" it will not tell you what they are. But I can hypothesize. Here is a mosaic of photographs of Mercury's surface from the MESSENGER spacecraft. It looks weird at the top and bottom because ...

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A quick search returns that wikipedia has an extensive list how different things are named on various celestial bodies. For Mercury's craters it quotes "Famous deceased artists, musicians, painters, authors". As source of its wisdom it gives the IAU working group on planetary system nomenclature as authoritive source for them - the source which ...

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