Neptune
49,528 km (30,775 mi)
Equatorial diameter
The farthest planet, an ice giant with supersonic winds. Diameter: 49,528 km, slightly smaller than Uranus.
Published
How big is that?
49,528 km is 3.9 times Earth and 35% of Jupiter.
Neptune is the 6th largest of the 39 Cosmic Scale objects, and the 6th largest of the 109 objects across all three SizeItUp games.
Size comparison
To scale, smallest to largest: Neptune in orange beside the Cosmic Scale objects nearest in size, in teal.
| Object | Size | vs Neptune |
|---|---|---|
| VenusEarth's neighbour, wrapped in thick clouds. | 12,104 km across | 24% of the size |
| EarthHome. Measured across the equator. | 12,756 km across | 26% of the size |
| Neptune | 49,528 km across | – |
| UranusAn ice giant that spins on its side. | 51,118 km across | about the same |
| Saturn (Planet only)The ringed giant. Its height here is the planet's own diameter; the rings stick out sideways. | 120,536 km across | 2.4× bigger |
In other units
| Metres | 49,528,000 |
|---|---|
| Kilometres | 49,528 |
| Miles | 30,780 |
How it's measured
Equatorial diameter. NASA Planetary Fact Sheet.
Planets spin, so they bulge at the equator: the equatorial diameter is a little larger than the distance from pole to pole.
Sources
- nssdc.gsfc.nasa.gov: Neptune: 49,528 km.
Checked against the source on .
Could you have guessed it by eye?
Neptune is one of the objects in Cosmic Scale, a daily size comparison game: you stretch a shape to the size you think is right beside one you know.