The closest planet to the Sun with a mean distance of 58 million kilometers. Revolving around the Sun every 88 days and rotating around its own axis every 56 Earth days, Mercury has only recently begun to be studied thoroughly.
Counter to the planet's name, based upon theoretical evidence, Mercury probably would contain iron and nickel.
Caused by deviating temperatures, Mercury's surface is covered with a layer of reddish iron dust. These metals, combined from the solar particles of the Sun, thus contribute to Mercury's high density compared to Mars, Venus, and the Earth.
The enormous range in temperatures cause erosion of exposed rock, which contributes to the layer of dust, which cloaks the surface. Deviating from a boiling 430 degrees Celcius during the day and -180 degrees Celcius during the planet's night cycle, Mercury does not follow expectations.