Key facts
- Scale fact
- 4,879 kmdiameter
- Estimated age
- ~4.5 billion years
- Composition
- Metal-rich silicate rock
- Temperature
- ~440 K mean surface
Mercury
4,879 kmdiameter
Visual creditMESSENGER 2008 / NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington / Public domainSource: Wikimedia Commons
Details
Mercury is the smallest planet in the Solar System and the closest one to the Sun. Because of its unusual spin-orbit rhythm, one Mercury solar day lasts 176 Earth days, which is longer than its 88-day year.
Mercury rotates three times for every two trips around the Sun. The resulting sunrise-to-sunrise day lasts 176 Earth days—twice its 88-day year—even though the planet completes one axial rotation in about 59 days. MESSENGER measurements also show that an iron-rich core occupies an unusually large share of the planet’s interior.
Links
- Editorial guides
- Universe journey
- Sun & inner planets
- Preset views
- Wikipedia
- Mercury on Wikipedia
Size neighbors
Objects near Mercury on the scale
Sources
References for Mercury
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Mercury — Wikipedia
- Visual reference: Wikimedia Commons (MESSENGER 2008 / NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington, Public domain)
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About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.