Reference image
Object guide
Neptune is an ice giant with very strong winds and weather patterns. Its deep blue color is caused by methane and other atmospheric components. Triton, its largest moon, has a retrograde orbit indicating capture. Neptune is approximately 49,244 km across.
How to observe Neptune
Neptune is best observed near opposition or greatest elongation as appropriate; steady seeing and repeated short observations reveal more than excessive magnification.
Scientific context
Useful scale comparisons are 3.865 Earth diameters, 1.137 g surface gravity, 164.791 Earth years per orbit. These values are rounded from the catalogue measurements shown on this page.
- Radius
- 24,622 km
- Diameter
- 49,244 km
- Mass
- 1.024E+26 kg
- Mean density
- 1.638 g/cm³
- Surface gravity
- 11.15 m/s² (1.137 g)
- Mean temperature
- -200°C
- Orbital period
- 60,190 days (164.791 years)
- Semi-major axis
- 30.05 AU
- Mean sunlight travel time
- 249.92 minutes
3.865 Earth diameters1.137 g surface gravity164.791 Earth years per orbit
Source: NASA Science (checked 2026-08-09). Values are rounded catalogue measurements.
24-hour altitude profile
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Interactive orbit model
Aug 13, 2026, 22:251×
Calculated positions / separate exploration scales