Mercury (planet)
Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of . Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material. Mercury's density is the second highest in the Solar System at 5.427 g/cm, only slightly less than Earth's density of 5.515 g/cm. If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm versus Earth's 4.4 g/cm.
List of directly imaged exoplanets
The data given for each planet is taken from the latest published paper on the planet to have that data. In many cases it is not possible to have an exact value, and an estimated range is instead provided. The least massive planet is Fomalhaut b, which has a mass of 2 M or less. The coldest and oldest is 59 Virginis b with a mean temperature of 240 °C and age of 100–500 million years.
This list includes the four members of the multi-planet system that orbit HR 8799.