Mercury is the smallest planet in our solar system and the closest planet to the sun. It has a dark gray, rocky surface, and is covered with a thick layer of dust. 

Features

Size: Mercury is slightly larger than Earth's Moon. 

Orbit: Mercury's orbit around the sun takes 88 days.

Surface: Mercury's surface is rough and cratered. 

Atmosphere: Mercury has a thin exosphere made up of oxygen, sodium, hydrogen, helium, and potassium. 

Moons: Mercury has no moons. 

Temperature: Surface temperatures on Mercury can exceed 800 °F (430 °C) at its hot poles. During its long nights, surface temperatures drop to about −300 °F (−180 °C). 

Observation 

Mercury appears as a morning or evening star from Earth.

It is very hard to see because of its proximity to the sun.

It can be observed at least twice a year: in spring at dusk and in autumn before dawn.

Other facts

Mercury is a terrestrial planet, meaning that it has a solid surface and is mainly made of silicate rocks or metals. 

Mercury is the most heavily cratered object in the solar system.