Key facts
- Scale fact
- 49,244 kmdiameter
- Estimated age
- ~4.5 billion years
- Composition
- Hydrogen, helium, water-ammonia-methane ices
- Temperature
- ~59 K cloud tops
Neptune
49,244 kmdiameter
Details
Neptune is the farthest planet from the Sun. Its winds are the fastest measured in the Solar System, driving methane clouds at more than 2,000 kilometers per hour.
Irregularities in Uranus’s predicted orbit led mathematicians to calculate the position of another planet, and observers found Neptune near that prediction in 1846. Voyager 2 remains the only spacecraft to visit it, measuring an atmosphere with storms and winds exceeding 2,000 kilometers per hour. Methane absorbs red light, but methane alone does not explain every detail of Neptune’s color or its difference from Uranus.
Links
- Editorial guides
- Universe journey
- Solar System
- Preset views
- Wikipedia
- Neptune on Wikipedia
Size neighbors
Objects near Neptune on the scale
Sources
References for Neptune
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.
- Neptune — Wikipedia
- Visual reference: Wikimedia Commons (Voyager 2 1989 / NASA / PDS / OPUS / Ardenau4, CC0 1.0)
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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.