Neptune-The Other Blue Planet, History, Characteristics of Neptune (For CBSE, ICSE, IAS, NET, NRA 2022)

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Neptune - The Other Blue Planet

  • Neptune is the eighth planet from the sun. It was the first planet to get its existence predicted by mathematical calculations before it was seen through a telescope on Sept. 23,1846.
  • Neptune is a fascinating world, and not much is known about it. Perhaps, it is because Neptune is the most distant planet from the sun
  • Irregularities in the orbit of Uranus led French astronomer Alexis Bouvard to suggest that the gravitational pull from another celestial body might be responsible.
  • Very few exploratory missions have ventured that far. Regardless, it is a planet full of wonder.
  • German astronomer Johann Galle then relied on subsequent calculations to help spot Neptune via telescope.
  • It is the only planet in the solar system that is found by mathematical prediction rather than empirical observation.
  • Previously, astronomer Galileo Galilei sketched the planet, but he mistook it for a star due to its slow motion.
  • In accordance with all the other planets seen in the sky, this new world was given a name from Greek and Roman mythology — Neptune, the Roman god of the sea.


  • In Roman mythology, Neptune is the god of the sea. The planet is seemingly named after the sea god owing to its blue colour.
  • It was observed after the discovery of Neptune, that its orbit was not in accordance with Newton՚s law. It was, therefore, predicted that there must be another distant planet perturbing Uranus՚s orbit.
  • Centuries earlier, in 1613, Galileo observed Neptune when it happened to be very near to Jupiter. But he disregarded it as a star.
  • Voyager 2 is the only spacecraft that has visited Neptune. Much of what we know today comes from this single encounter.

Characteristics of Neptune

Characteristics of Neptune
  • While Neptune is of interest because it is in our own solar system, astronomers are also interested in learning more about the planet to assist with exoplanets studies.
  • Some astronomers are interested in learning about the habitability of worlds that are somewhat bigger than Earth.
  • Neptune is dark, cold, and windy.
  • It՚s the last of planets in our solar system.
  • Photos of Neptune reveal a blue planet, and it is often dubbed an ice giant, since it possesses a thick, slushy fluid mix of water, ammonia and methane ices under its atmosphere and is roughly 17 times Earth՚s mass and nearly 58 times its volume, according to a NASA fact sheet. Neptune՚s rocky core alone is thought to be roughly equal to Earth՚s mass, NASA says.
  • The composition of Neptune is similar to Uranus – ice and rock with about 15 % hydrogen and a little helium. Its atmosphere is made up of hydrogen, helium, and methane.
  • Despite its great distance from the sun, which means it gets little sunlight to help warm and drive its atmosphere, Neptune՚s winds can reach up to 1,500 mph (2,400 km/h) , the fastest detected yet in the solar system.
  • Neptune՚s blue colour is primarily due to the absorption of red light by methane in the atmosphere.
  • Neptune winds are the fastest in the solar system reaching a speed of 2000 km/hr.

Structure and Surface

  • Atmospheric composition (by volume) : hydrogen, 80 percent; helium, 19.0 percent; methane, 1.5 percent
  • Six rings encircle Neptune.
  • Magnetic field: Roughly 27 times more powerful than Earth՚s
  • Composition: The overall composition of Neptune is, by mass, thought to be about 25 percent rock, 60 to 70 percent ice, and 5 to 15 percent hydrogen and helium, according to Tristan Guillot, author of “Interiors of Giant Planets Inside and Outside the Solar System” in the journal Science.
  • It is made of thick soup of water, ammonia, and methane flowing over a solid core.
  • Internal structure: Mantle of water, ammonia, and methane ices; Core of iron and magnesium-silicate
  • It has a thick windy atmosphere.

Time on Neptune

  • One day on Neptune is equivalent to 16 hours
  • To complete one rotation around the sun it takes about 165 Earth years.

Neptune Neighbours

  • Neptune has 13 moons
  • Neptune is the eighth and most distant planet from the sun.
  • This means that Uranus is its only neighbouring planet.

Neptune Satellites

  • Neptune is known to have 14 moons; 7 named one.
  • The table below shows the list of satellites and rings of Neptune.
Neptune Satellites

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