Mercury is the most minor planet in the solar system. It has a solid, rocky surface, a large iron core for about 85% of its radius, and a thin atmosphere. The surface of Mercury resembles the Earth's moon (heavily cratered). Mercury orbits the sun the fastest out of all planets. There are extreme weather variations. Mercury has no moons.
Mercury has a thick atmosphere of oxygen, sodium, hydrogen, helium, and potassium. Its temperature swings are dramatic. The side that faces the sun can reach 800 degrees Fahrenheit.
Mercury has smooth plains resembling lunar maria, extensive impact craters, and lobate scarps.
Mercury can potentially support life, particularly in the permanently shadowed polar regions. Water ice and subsurface volatiles could create an environment suitable for life.
NASA's Mariner 10 made three flybys, mapping about 45% of the planet's surface and revealing Mercury's heavily cratered, moonlike surface.
MESSANGER was launched to study Mercury.
MESSANGER became the first spacecraft to Orbit Mercury and provided detailed data about its surface, topography, and magnetic field.
BepiColombo (a mission between the European Space Agency and the Japan Aerospace Exploration Agency) was launched in 2026 to deliver two probes into Mercury orbit.