57 Interesting Facts About Neptune

Last updated on January 15th, 2024

Neptune is a dark and a cold planet. It is among the eight planets in the solar system. Neptune has some features and characteristics that set it apart from the other planets. Neptune is located about 2.8 billion miles (4.5 billion kilometres) from the Sun, making it a distant neighbour. It takes about 164.8 Earth years to complete one orbit around the Sun. Neptune is named after the Roman god of the Sea because of its bluish appearance. Neptune was initially called “Le Verrier” after the name of the scientist – Jean Joseph Le Verrier – who discovered it. However, this name of the planet was abandoned and it was finally named Neptune. With these facts let us learn more about the most dense of the gas giants – “Neptune.”

Facts about Neptune


1. Neptune is the eight and the farthest planet from the sun. However, in 1930, after the discovery of Pluto, the title of the most distance planet from the Sun was snatched from Neptune and was given to Pluto. However, once again, in 2006, when Pluto was re-classified as a dwarf planet, Neptune became the most distant planet from the Sun. (Order of the planets from the sun: MercuryVenusEarthMarsJupiterSaturnUranus, Neptune, and Pluto (the dwarf planet). 


2. Neptune was not known to the ancients, and until 1846, its position was determined with the help of mathematical predictions. Galileo had predicted the presence of a star in his drawings however he did not conclude that it was actually a planet.


3. On September 23, 1846, German astronomer Johann Galle visually confirmed the existence of Neptune using Le Verrier’s calculations. The discovery was hailed as a significant triumph for celestial mechanics.

Distance in Astronomical unit

4. Neptune is 30 AU from the Sun while the Earth is 1 AU. 

5. Neptune’s discovery contributed to refining the value of the astronomical unit (AU), the average distance between the Earth and the Sun. Observing Neptune’s orbit provided a more accurate measure of the AU (149,597,870.7 km (92,955,807.3 miles).

Ice or Gas?

6. Neptune is the smallest of the ice giants and the most densest of the gas giants. Uranus is the other ice giant.

No solid surface

7. Because Neptune is a gas giant, there is no solid surface on Neptune for a spacecraft to land on the planet.

Neptune. Neptune fact file
This picture of Neptune was produced from the last whole planet images taken through the green and orange filters on NASA’s Voyager 2 narrow angle camera. The images were taken at a range of 4.4 million miles from the planet, 4 days and 20 hours before closest approach. The picture shows the Great Dark Spot and its companion bright smudge; on the west limb the fast moving bright feature called Scooter and the little dark spot are visible. These clouds were seen to persist for as long as Voyager’s cameras could resolve them. North of these, a bright cloud band similar to the south polar streak may be seen. Photo credit – JPL/NASA

Sighting the planet in the sky

8. Neptune cannot be seen in the sky with the naked eye because of its extreme distance from the Earth.

Diameter and Mass

9. Neptune is the fourth largest planet in terms of diameter and third largest in terms of mass.

Neptune vs Jupiter

10. Did you know that Neptune has the second largest gravitational force in the solar system after Jupiter?

Around the Sun

11. Neptune takes 165 Earth years to complete its orbit around the sun.

Maiden orbit

12. Since its discovery in 1946, Neptune completed its first orbit around the Sun in 2011.

13. Neptune’s rotation period is not constant, and different parts of its atmosphere rotate at varying speeds. This non-uniform rotation is known as differential rotation.

One day on the planet

14. The length of a day on Neptune is approximately 16 hours.

Pluto vs Neptune

15. During the time Neptune makes three orbits around the Sun, Pluto makes two.

Uranus vs Neptune

16. Uranus is slightly bigger than Neptune.

The only neighbour

17. Uranus is Neptune’s only neighbouring planet.

Neptune vs Earth – size comparison

18. It would take 60 Earth’s to completely occupy the space available on Neptune.

Neptune vs Earth – gravitational force

19. Neptune’s gravitational force is only 17% stronger than that of the Earth. Thus, Neptune is the only planet in the solar system that has Earth-like gravity.

20. Neptune’s gravity played a crucial role in the early formation of the solar system by preventing Uranus and Neptune from colliding and scattering other objects, including dwarf planets, into the outer solar system.

21. Neptune’s gravitational influence occasionally disturbs the orbits of asteroids and comets in the Kuiper Belt, leading to the possibility of these objects being scattered into the inner solar system.

Magnetic field

22. Neptune’s magnetic field is 27 times more powerful than that of the Earth.

23. Unlike the Earth, Neptune’s magnetic field is tilted relative to its rotation axis. This tilt creates a magnetodisk, a region where charged particles from the solar wind are trapped and spiral along magnetic field lines.

Which color?

24. The characteristic color of Neptune is blue which is due to the presence of Methane on the planet. Uranus, on the other hand, is greenish-blue.

Moons are many

25. Neptune has fourteen (14) officially confirmed moons.

Latest moon

26. Its largest moon was discovered just 17 days after its discovery. Neptune’s fourteenth (14th) moon was discovered on July 1, 2013, during a fresh analysis of the images collected by the Hubble Space Telescope. The moon was spotted nearly 150 times in the images that were collected during 2004 and 2009. Scientists estimate that the moon is just 12 miles wide. 

Neptune’s biggest moon

27. Triton, Neptune’s biggest moon, revolves in an opposite direction to that of Neptune’s other moons. It is the only large moon in the solar system that has a retrograde orbit.

Today’s moon, Tomorrow’s ring

28. Triton is slowly spiraling inward towards the planet. It is estimated that Triton, after a few billion years, will eventually be torn apart by the planet’s gravitational force and a ring will be formed as a result.

29. Triton’s atmosphere has been observed to “blink” or vary in brightness over time. This phenomenon is not fully understood and adds to the enigma of Triton’s atmosphere.

30. In 1989, it was discovered that Triton has geysers that spew nitrogen gas into space. These geysers contribute to the thin atmosphere around Triton and create dark streaks on its surface.

31. Triton’s eccentric orbit around Neptune results in tidal forces that generate heat within the moon. This tidal heating is a significant factor in maintaining Triton’s geologically active surface.

32. The gravitational interactions among Neptune’s moons can create chaotic resonances, causing their orbits to become unpredictable over long periods.

33. Galatea, one of Neptune’s small moons, is in a stable orbital resonance with another moon, Larissa. This means their orbital periods are related in a simple mathematical ratio.

34. The average surface temperature of Neptune is minus 214 degree Celsius.

Coldest of all

35. Neptune also has the credit of being the coldest planet in our Solar System. The temperature on the planet can get as low as minus 221°C (The lowest natural temperature ever directly recorded at ground level on the Earth is minus 89.2°C, which was at the Soviet Vostok Station in Antarctica.)

Exploration by Voyager 2

36. Just one mission has been sent to Neptune, Voyager 2, which conducted a flyby in 1989. Maybe because of its long distance from the Earth or due to the lack of interest of the scientific community because of the non-availability of conditions to sustain human life on Neptune.

37. Voyager 2, while approaching Neptune, experienced difficulties in receiving radio signals due to the planet’s powerful magnetosphere. The odd signal interruptions provided valuable information about Neptune’s magnetic field.

Wind speed comparison

38. Winds on Neptune can be three times faster than that on Jupiter and nine times faster than that on the Earth. And scientists are amazed as to why the winds on the planet blow so fast.

A Monster Dark Spot

39. Great Dark Spot in the southern atmosphere of Neptune was first recorded by Voyager 2 in 1989. Wind speeds upward of 1500 miles per hour were recorded during this storm. However, the storm only lasted for 5 years, because when in 1994, the Hubble Space Telescope was used to view the dark Spot, the Dark Spot was not there anymore.

40. Neptune experiences incredibly strong winds, with speeds that can reach up to 1,500 miles per hour (2,400 kilometers per hour) in its equatorial region. Understanding these winds helps scientists probe the planet’s atmospheric circulation.

41. Neptune has a thick atmosphere composed primarily of hydrogen, helium, and methane. The atmosphere extends to great depths, and it’s believed that beneath the visible cloud tops, there may be an ocean of liquid water mixed with ammonia and methane.

42. Researchers have identified Rossby waves in Neptune’s atmosphere, which are large-scale meanders in the jet stream. These waves contribute to the planet’s atmospheric circulation and weather patterns.

43. Unlike the stormy atmospheres of gas giants like Jupiter, Neptune is surprisingly quiet when it comes to radio emissions. The reason for this relative radio silence is not well understood.

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