Mercury

Mercury orbits closest to the Sun, and no other planet is smaller.[1]

History

Mariner 10 made the first spacecraft visit to Mercury.[2]

Findings

MESSENGER made three close passes, then orbited Mercury for four years.[2] A year on Mercury lasts 88 Earth days.[1] NASA reports Mercury has a radius of 2,440 kilometres.[1] JPL lists Mercury's mean radius as 2440.53 km.[3] Mercury has water ice in craters that stay permanently in shadow.[4]

Current status

Mercury has no natural moons.[1] Mercury has no rings.[1]

Sources

  1. Mercury | NASA. Licence: facts-only (Track B), no text or images reused. Attribution: NASA.
  2. Mercury | NASA. Licence: facts-only (Track B), no text or images reused. Attribution: NASA.
  3. JPL Solar System Dynamics: Planetary Physical Parameters. Licence: facts-only (Track B), no text reused. Attribution: NASA/JPL-Caltech.
  4. BepiColombo factsheet | European Space Agency. Licence: facts-only (Track B), no text reused. Attribution: European Space Agency.

Evidence as of 2026-11-01.