Encyclopedia of Astrobiology

2015 Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James (Jim) CleavesII, Daniele L. Pinti, José Cernicharo Quintanilla, Daniel Rouan, Tilman Spohn, Stéphane Tirard, Michel Viso


  • Jörn Helbert
Reference work entry
DOI: https://doi.org/10.1007/978-3-662-44185-5_958


Mercury is the innermost  planet and the smallest of the four  terrestrial planets. It is the only terrestrial planet except Earth to have a global magnetic field. Mercury shows the most extreme surface temperature variations of all terrestrial planets. The average surface temperature is 442.5 K, with dayside temperatures up to 700 K and nightside temperatures down to 80 K. Mercury has a tenuous exosphere containing hydrogen, helium, oxygen, sodium, calcium, and potassium. This exosphere is not stable – atoms are continuously lost and replenished from a variety of sources.


So far, only two spacecrafts have visited Mercury. The NASA mission Mariner 10 made 3 flybys in 1974 and 1975. The NASA mission MESSENGER made three flybys between 2007 and 2009 and has entered orbit around the planet in March 2011. The ESA mission BepiColombo will observe the planet from orbit starting 2019. Observing Mercury from  Earthis challenging. While it is bright, ranging from −2.3 to...


Core Exosphere NASA mission Mariner 10 NASA mission Messenger 
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References and Further Reading

  1. Balogh A, Ksanfomality L, von Steiger R (2008) Space science series of ISSI. Mercury, vol 76. Springer-Verlag New York. ISBN 978-0-387-77538-8Google Scholar
  2. Solomon SC (2003) Mercury: the enigmatic innermost planet. Earth Planet Sci Lett 216(4):441–444ADSCrossRefGoogle Scholar
  3. Sprague A, Strom R (2003) Exploring Mercury: the iron planet. Springer, BerlinGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.DLRInstitut für PlanetenforschungBerlinGermany