Planet · Ice giant

Neptune

Solar System

Scientific overview

Neptune is a ice giant in orbit around The Sun, at a mean distance of 4,495.1 million km from the Sun.

Physical characteristics

Mass	102 ×10²⁴ kg
Diameter	49,528 km
Radius	24,764 km
Density	1.638 g/cm³
Surface gravity	11 m/s²
Escape velocity	23.5 km/s
Rotation period	16.1 h
Mean temperature	-200 °C

Orbit

Distance from Sun	4,495.1 million km (30.047 AU)
Orbital period	163.72 years
Perihelion	4,444.5 million km
Aphelion	4,545.7 million km
Eccentricity	0.011
Orbital inclination	1.8°
Axial tilt	28.3°
Orbital velocity	5.4 km/s

Moons (3)

Exploration

Voyager 21977

Sources

Facts on this topic will be cited from these primary and reference sources.

NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
NASA JPLJet Propulsion Laboratory / Solar System Dynamics
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.

Quick facts

Type: Ice giant
System: The Sun
Moons: 14
Ring system: Yes

Provenance & sources

review 2026.1

Asteria Scientific Review Process · verification: sourced · accurate

High evidenceconfirmed
Neptune is the eighth and most distant known planet, an ice giant with the strongest sustained winds measured in the Solar System.
Source: NASA (NSSDCA) — NASA Planetary Fact Sheet · Public domain (US Government work)
- NASA Planetary Fact Sheet, Planetary Fact Sheet

Reviewed by the internal Asteria Scientific Review Process — not an external institutional review. See the evidence framework and authority dashboard.

Scientific citations

Real, source-backed references — primary papers first, then datasets and institutional sources. Formatted through the citation engine; nothing is fabricated.

DatasetApproximate Positions of the Planets

NASA Jet Propulsion Laboratory (Caltech)

Cite (APA / BibTeX)

NASA Jet Propulsion Laboratory (Caltech) (n.d.). Approximate Positions of the Planets. NASA Jet Propulsion Laboratory (Caltech). https://ssd.jpl.nasa.gov/planets/approx_pos.html

@misc{cite:jpl-approx-positions,
  title        = {Approximate Positions of the Planets},
  organization = {NASA Jet Propulsion Laboratory (Caltech)},
  year         = {n.d.},
  url          = {https://ssd.jpl.nasa.gov/planets/approx_pos.html},
  note         = {Public-domain Keplerian orbital elements and rates (Standish) — the method behind the computed planet positions, rise/set, and visibility.}
}

DatasetNeptune Fact Sheet

NASA Goddard — NSSDCA

Cite (APA / BibTeX)

NASA Goddard — NSSDCA (n.d.). Neptune Fact Sheet. NASA Goddard — NSSDCA. https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html

@misc{cite:factsheet-planet-neptune,
  title        = {Neptune Fact Sheet},
  organization = {NASA Goddard — NSSDCA},
  year         = {n.d.},
  url          = {https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html},
  note         = {Physical and orbital parameters for Neptune.}
}

Institutional pageNeptune — NASA Solar System Exploration

NASA

Cite (APA / BibTeX)

NASA (n.d.). Neptune — NASA Solar System Exploration. NASA. https://science.nasa.gov/

@misc{cite:nasa-planet-neptune,
  title        = {Neptune — NASA Solar System Exploration},
  organization = {NASA},
  year         = {n.d.},
  url          = {https://science.nasa.gov/},
  note         = {NASA overview of Neptune.}
}

Quality & authority

75%

Reviewed

Completeness: Complete
Source coverage: Complete
Citation coverage: Complete
Relationship coverage: Complete
Review coverage: Complete
Image coverage: None

Data from the NASA Planetary Fact Sheet & JPL (public domain). See source quality.

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Sources

Facts on this topic will be cited from these primary and reference sources.

NASANational Aeronautics and Space Administration

Mission data, planetary science, space telescopes, and public-domain imagery.

Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

NASA JPLJet Propulsion Laboratory / Solar System Dynamics

Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.

NASA Jet Propulsion Laboratory (Caltech) (n.d.). Approximate Positions of the Planets. NASA Jet Propulsion Laboratory (Caltech). https://ssd.jpl.nasa.gov/planets/approx_pos.html @misc{cite:jpl-approx-positions, title = {Approximate Positions of the Planets}, organization = {NASA Jet Propulsion Laboratory (Caltech)}, year = {n.d.}, url = {https://ssd.jpl.nasa.gov/planets/approx_pos.html}, note = {Public-domain Keplerian orbital elements and rates (Standish) — the method behind the computed planet positions, rise/set, and visibility.} }

NASA Goddard — NSSDCA (n.d.). Neptune Fact Sheet. NASA Goddard — NSSDCA. https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html @misc{cite:factsheet-planet-neptune, title = {Neptune Fact Sheet}, organization = {NASA Goddard — NSSDCA}, year = {n.d.}, url = {https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html}, note = {Physical and orbital parameters for Neptune.} }

NASA (n.d.). Neptune — NASA Solar System Exploration. NASA. https://science.nasa.gov/ @misc{cite:nasa-planet-neptune, title = {Neptune — NASA Solar System Exploration}, organization = {NASA}, year = {n.d.}, url = {https://science.nasa.gov/}, note = {NASA overview of Neptune.} }