Overview of Neptune

Neptune is the eighth and most distant planet from the Sun in the Solar System. It is the fourth largest planet in diameter and the third largest in volume.

Neptune has the largest density of the planets in the solar system. Neptune has 17 times the mass of the Earth and is slightly larger than the mass of Uranus (approximately equal to 15 times that of the Earth).

Neptune rotates on orbit around the Sun at an average distance of 30.1 AU, about 30 times the distance between the Earth and the Sun.

Neptune is similar in structure to Uranus, but is different from giant gas planets like Jupiter and Saturn. Neptune's atmosphere contains the basic components of hydrogen and helium, a handful of hydrocarbons and perhaps nitrogen, similar to that of Jupiter or Saturn. However its atmosphere contains a greater proportion of "ice" molecules such as water, ammonia, and methane. Therefore astronomers occasionally classify Uranus and Neptune into giant ice planets to emphasize this difference.

Neptune has the largest density of the planets in the solar system.

The structure of Neptune

Neptune has a mass of 1,0243 × 1026 kg, which lies between the Earth and the giant gas planets: its mass is 17 times the mass of the Earth but only 1/19 of that of Jupiter. Gravity on its surface is only smaller than that of Jupiter.

The inner structure of Neptune is similar to that of. Its atmosphere accounts for about 5% to 10% of the planet's mass and is about 10% to 20% of the planet's radius, falling as deep as 10 GPa to 100,000 times the atmospheric pressure on Earth.

Neptune's core has components including iron, nickel and silicate, and has a mass model of 1.2 times the mass of the Earth.

The atmosphere of Neptune

At high altitudes, Neptune's atmosphere contains 80% hydrogen and 19% helium. There is also a small amount of methane molecule. Traces of methane were also discovered when scientists observed typical absorption spectra of methane at wavelengths above 600 nm, in the red and infrared wavelength domain.

The atmosphere of Neptune is divided into two main regions; The lower troposphere with temperature in this layer decreases with elevation, and the upper stratosphere with temperature increases with elevation.

Neptune's orbit

The average distance between Neptune and the Sun is 4.5 billion kilometers (about 30.1 AU), and the orbital cycle is 164.79 years for the Earth to change within ± 0.1 years.

The plane of the Neptune's elliptical orbit is 1.77 ° above the Earth's orbit. Since the eccentricity of its orbit is 0.011, the distance to the Sun varies within 101 million km between the near-point and the orbit.

Neptune's trajectory greatly influenced areas outside this planet's orbit, such as the Kuiper belt.

Climate on Neptune

One of the differences between Neptune and Uranus is the degree of climate phenomena on the two planets. When Voyager 2 flew over Uranus in 1986, through the visible wavelength, the planet appeared almost uniform and still. On the contrary, Neptune had strong activity in the atmosphere when Voyager 2 passed since 1989.

Weather on Neptune is characterized by a system of extremely strong storms, with wind speeds sometimes approaching 600m / s - almost reaching supersonic speeds for air currents. Most winds on Neptune blow in the opposite direction to the rotation of the planet.

Neptune's planetary belt

Neptune also has a planetary belt system, although they are much dimmer than Saturn's belt. The belts contain ice particles coated with silicate or carbon-based materials, and are the main reason for the belts to be red in color.

Compare the size of the Star King and Earth.

Storm on Neptune

In 1989, Scarlet Big, a swirling storm with an area of ​​13000 × 6600 km was discovered by Voyager 2. This storm is similar in form to Jupiter's Big Red Stain.

The Small Dark Spot is a swirling storm in the southern hemisphere, the second strong storm observed during the flight over 1989. Initially the storm was completely dark, but when Voyager 2 approached the planet, it was discovered the storm formed a bright center and can be seen in most high-resolution photos.

Dark spots appear in the troposphere at lower elevations than bright clouds in Neptune's atmosphere, so they appear as taller clouds of dark clouds. They are stable characteristics that can last for several months, and have a whirlpool structure. Dark spots can dissipate as they approach too close to the equator or through an unexplored mystery mechanism.

Satellites of Neptune

Neptune has 14 known satellites. Its largest satellite, the Triton, accounts for more than 99.5% of the mass of all objects orbiting Neptune [116] and is the only spherical satellite.

Explore Neptune

Voyager 2 approached the nearest Neptune star on August 25, 1989. Since this was the last major planet the ship visited, program managers decided to allow the ship to fly over the Triton satellite, because they do not need to take into account the future trajectory of the ship, similar to Voyager 1 flying over Saturn and making Titan flight.

In 2003, there was a proposal in NASA's Future Mission Plan to launch a Neptune orbiter carrying an atmospheric probe like the Cassini mission. The program was jointly implemented by JPL Jet Propulsion Laboratory and California Institute of Technology, but the project was not approved.