Mercury

Properties:

Mass: 3.3011 * 10²³ kg

Equatorial Radius: 2,439.7 km

Semi-major Axis: 57,909,050 km(0.387 AU)

Orbital Period: 87.9691 days(0.241 yr)

Rotational Period: 58.646 days

Surface Gravity: 3.7 m/(s²)

Etymology: Mercurius(Roman God of commerce, messenger of the gods)

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Mercury is the closest planet in our Solar System to the Sun, which means that it has the smallest orbital period out of the 8 planets. It also is the smallest planet in the Solar System(equatorial radius listed above).

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Mercury's orbit has a 3:2 spin-orbit resonance, meaning that the ratio between the orbital period of Mercury and the rotational period of Mercury is 3:2. In other words, if Mercury completed 2 orbits around the Sun, it would complete 3 rotations around its own axis.

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There is very minor scientific evidence that Mercury supported primitive microorganisms at one point or another.

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Surface temperatures are quite extreme, ranging from 100-700 K, on Mercury due to the lack of an atmosphere and its relative proximity to the Sun. However, at the poles, there are deep craters that store frozen ice water so ice exists on the Mercurian surface.

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On the topic of craters, Mercury is known to have many craters and many of them are impact craters that were formed around the time when Mercury was formed 4.6B years ago. Mercury is believed to gain most of its craters during the hypothesized Late Heavy Bombardment, a theorized time period between 3.8B and 4.1B years ago where a large number of asteroids collided with the terrestrial planets(Mercury, Venus, Earth, Mars). However, this theory isn't entirely concrete because it has yet to be sufficiently proven true.