The Cratered World Of Mercury

This is my short guide to Mercury. In it, I discuss its major attributes and origin.

The Cratered World Of Mercury

Mercury is very much like our Moon. It is a heavily cratered body with no atmosphere. It is the nearest planet to the Sun. It gets very hot since it spends a lot of time close to the Sun in its orbit. Its orbit is quickest when it is closest to the Sun. By that same logic, its orbit is slowest the farther away it gets from the Sun in its orbit. It is easiest to see when it is far away from the Sun.

Its Structure

Its mass is much smaller than our Earth. It is around \( \frac{1}{18} \) the mass of the Earth for reference. This makes it the smallest planet in our solar system. However, it is pretty dense for being so small. Its density is \( 5.4 \frac{g}{cm}^3 \). This tells us that the core of Mercury must be made up of heavy metals. This makes it very interesting for us to study. The most likely composition of its core is some mix of nickel and iron. This probably accounts for much of its mass and density. A small magnetic field has been detected so at least part of the core should be liquid. 

Density = \[ \frac{mass}{\frac{4}{3}\pi(R^3)} \]

Rotation

Rotation is how long it takes something to rotate. The rotation of Mercury is 59 days. This makes for a very long day! The effect of this long rotation makes for wide temperature changes. Another unique attribute is that a day on Mercury is around \( \frac{2}{3} \) of a year on this same planet. 

Surface

The surface of Mercury has been mapped by a couple different spacecraft, Mariner and the Messenger. Its surface looks very much like our Moon. It is deeply cratered all over. It used to be geologically active. We can infer this by the presence of old volcanoes and its partially liquid core. However, there does not appear to be any plate tectonics happening. 

Origin

Mercury is composed of a large percentage of metals. It should have a similar percentage of metals and silicates to that of Earth, though. There is no definite consensus of why Mercury is like this. Most people knowledgeable about this topic think large impacts broke large pieces of its surface off or the Sun’s heat evaporated the more sensitive silicates away. It could also be a combination of these two scenarios.