Neptune size and scale context

Neptune is the outermost giant planet in the Solar System. It is the windiest world known, with methane-cloud systems racing through its atmosphere at speeds above 2,000 kilometers per hour. Read its scale context, comparisons, and journey links on the canonical object page.

CallistoGalilean moon·4,821 km

MercuryTerrestrial planet·4,879 km

TitanLarge icy moon·5,150 km

GanymedeGalilean moon·5,260 km

MarsTerrestrial planet·6,779 km

VenusTerrestrial planet·12,104 km

EarthTerrestrial planet·12,742 km

NeptuneIce giant planet·49,528 km

UranusIce giant planet·50,724 km

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Planets

Earth

Earth is the rocky planet on which we live and the most familiar anchor for planetary scale. It remains the only world known to host life, with long-lived surface oceans that have shaped both its geology and its atmosphere.

Scale fact12,742 kmdiameter

Object class: Terrestrial planet
Composition: Silicate rock and iron core
Temperature: ~288 K mean surface
Estimated age: ~4.54 billion years
Host: Sun

Planets

Neptune

Neptune is the outermost giant planet in the Solar System. It is the windiest world known, with methane-cloud systems racing through its atmosphere at speeds above 2,000 kilometers per hour.

Scale fact49,528 kmdiameter

Object class: Ice giant planet
Mass: ~17 Earth masses
Host: Sun
Estimated age: ~4.5 billion years
Composition: Hydrogen, helium, water-ammonia-methane ices
Temperature: ~59 K cloud tops

Planets

Uranus

Uranus is an ice giant that rotates tipped over on its side, with its spin axis tilted by about 98 degrees. That extreme tilt makes its seasons unlike any other planet’s, leaving each pole pointed toward the Sun for decades at a time during its 84-year orbit.

Scale fact50,724 kmdiameter

Object class: Ice giant planet
Mass: ~14.5 Earth masses
Host: Sun
Estimated age: ~4.5 billion years
Composition: Hydrogen, helium, water-ammonia-methane ices
Temperature: ~76 K cloud tops