OVERVIEW
] PLANETNeptune is an . It orbits the Sun at a mean distance of 30.0699 . It has a mass of 17.15 and a mean radius of 3.86 · 24 622 . It was discovered in 1846.
Found by mathematics before anyone looked: predicted from wobbles in the orbit of Uranus, then spotted within a degree of where the calculations said it would be. Its winds are the fastest in the Solar System.
- WHAT IT IS
- Ice giant
- HOW FAR
- 30.07
- HOW BIG
- 3.86 · 24 622
- ONE ORBIT TAKES
- 165
Its average distance from the Sun, not from Earth.
Its mean radius: half the width across.
One trip round the Sun.
THE MODEL
] CATALOGUED RADIUSCALCULATED · NOT AN OBSERVATION · CATALOGUED RADIUS · DENSITY 1.64 G/CM³ FROM MASS AND RADIUS · GEOMETRIC ALBEDO 0.410 · ICE GIANT · RADIUS 24 600 KM · LIT FROM WHERE THE SUN IS · TURNING ABOUT ITS OWN POLE · SURFACE FROM A GLOBAL MAP · LONGITUDES NOT REGISTERED
Drawn from the catalogued radius and from the same properties the picture at the top of this page uses, at the distance a flight to it would stop. It has 2 rings, and they are not in this picture: the outermost reaches 2.6 times the body's own radius, and every band out there is either narrower than the line it would be drawn as or too thin to darken what is behind it. They are in the model, at their catalogued edges; the frame is set on the planet, because widening it to hold them would trade most of the planet for a piece of empty sky. The surface is a global map rather than a pattern — a mosaic of real images, wrapped on by latitude and longitude. It is from the only spacecraft ever to have passed, which found an almost featureless disc; what banding there is has been saturated by the texture's publisher, who also filled the gaps in the coverage. Where it sits round the axis claims nothing: what a map of a fluid envelope shows is weather, and the clouds in this one have moved since it was taken. The map comes from Solar System Scope, under CC BY 4.0. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, at their real positions and drawn from where the camera actually is — so the constellations are wrong, and that is the point. This is the sky from there, not the sky from here.
IMAGES
] 4 FRAMES- NASA / Voyager 2 / PDS / OPUS / Ardenau4
CC0 - NASA
Public domain - NASA / JPL / Voyager-ISS / Aster Cowart
Public domain - NASA / Jet Propulsion Lab
Public domain
OBSERVING
] FROM WHERE YOU AREWhat it takes to see Neptune for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when Neptune is worth going out for.
THROUGH AN EYEPIECE
] 150 MM TELESCOPE · 25 MM EYEPIECEToo faint for your eyes alone. Binoculars reach it. Today it is 2.35″ across. It stops being a point of light at about 26×, and at 48× it is a small round disc.
- 48×
- 1.08
- 1.25
- 13.0
- 2.35
- SHOWS A DISC FROM
- 26×
- RINGS ACROSS
- 6.01
- MAGNITUDE TODAY
- 7.81 · within reach
The rings reach 6.01″ from edge to edge. What decides whether there is anything there to look at is the material rather than the reach: the densest band, Adams, is 0.0024″ wide on the sky — set that against the above — and its of 0.1 stops 9.5% of the light passing through it.
Its largest moons swing out to 3.51″ for Larissa, 5.61″ for Proteus, 16.9″ for Triton and 4.4′ for Nereid, at their widest. Every one of them gets further out than this equipment separates. How bright they are is another question, and one the catalogue does not answer: it publishes no magnitude for any moon.
Computed for 2026-09-11 from the centre of the Earth, and from the mean radius the catalogue holds. A distance changes daily, so this width is a fact about that date and not about the body.
CATALOG DATA
] 13 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT KIND OF THING IT IS
What the object is in itself, rather than how it happens to look from here.
- Mean temperature
- −200
- Rotation period
- 16.11
HOW BRIGHT IT IS
What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.
- Geometric albedo
- 0.41
- Bond albedo
- 0.29
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- North pole (RA)
- 299.36
- North pole (Dec)
- 43.46
THE ORBIT
The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.
- Orbital period
- 164.8
- Eccentricity
- Inclination
- 1.77
- Longitude of ascending node
- 131.78
- Longitude of perihelion
- 44.96
- Mean longitude
- −55.12
- Element epoch
- 2451545.0000
ALSO KNOWN AS
] 1 DESIGNATIONS- Common name Neptune
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Neptune [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/neptune
@misc{spacecatalog_neptune,
author = {{SpaceCatalog}},
title = {{Neptune}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/neptune},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from SpaceCatalog curated data.}
}The values above were taken from SpaceCatalog curated data — CC-BY-4.0. Citing this page does not replace citing that catalogue.