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Neptune
Neptune
Orbital characteristics
Aphelion

30.44 AU

Perihelion

29.77 AU

Semi-major axis

30.1 AU

Eccentricity

0.011214269

Orbital

164.79 years

Synodic period

367.49 days

Average orbital speed

5.43 km/s

Inclination

1.767975° to Ecliptic,
6.43° to Sun’s equator,
0.72° to Invariable plane

Longitude of ascending node

131.794310°

Argument of perihelion

265.646853°

Satellites

13

Physical characteristics
Flattening

0.0171

Surface area

14.98 Earths

Mass

17.147 Earths

Mean density

1.638 g/cm³

Equatorial surface gravity

1.14 G

Escape velocity

23.5 km/s

Sidereal rotation period

0.6713 days

Equatorial rotation velocity

2.68 km/s

Axial tilt

28.32°

North pole right ascension

299.3°

North pole declination

42.950°

Albedo

0.290

Surface temp.

55 to 72 K

Apparent magnitude
Angular diameter

2.2 to 2.4

Atmosphere
Surface pressure

0.1 to 1 Mbar

Compositions

hydrogen,
helium,
methane,
ammonia,
water

Neptune is the eighth planet from the sun at a distance of about 4.5 billion km (2.8 billion miles) or 30.07 AU.[1]

OrbitEdit

One day on Neptune takes about 16 hours (the time it takes for Neptune to rotate or spin once). Neptune makes a complete orbit around the sun (a year in Neptunian time) in about 165 Earth years (60,190 Earth days).[1]

AtmosphereEdit

Neptune's atmosphere is made up mostly of hydrogen (H2), helium (He) and methane (CH4).[1]

CompositionEdit

Neptune is a sister ice giant to Uranus. Neptune is mostly made of a very thick, very hot combination of water (H2O), ammonia (NH3), and methane (CH4) over a possible heavier, approximately Earth-sized, solid core.[1]

MoonsEdit

Neptune has 13 moons. Neptune's moons are named after various sea gods and nymphs in Greek mythology.[1]

RingsEdit

Neptune has six rings.

MissionsEdit

Voyager 2 is the only spacecraft to have visited Neptune.[1]

FactsEdit

  • Neptune crosses orbits with Pluto once in awhile.
  • Sometimes, during the course of Neptune's orbit, dwarf planet Pluto is actually closer to the sun, and us, than Neptune. This is due to the unusual elliptical (egg) shape orbit of Pluto.[1]

ReferencesEdit

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 https://solarsystem.nasa.gov/planets/neptune/needtoknow