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About Neptune Planet | Solar System

Neptune

Neptune is dark, cold, and very windy. It's the last of the planets in our solar system. It's more than 30 times as far from the sun as Earth is. Neptune is very similar to Uranus. It's made of a thick fog of water, ammonia, and methane over an Earth-sized solid center. 
Neptune Planet
Neptune Planet
Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. Neptune orbits the Sun once every 164.9 years at an average distance of 30.1 au (4.5 billion km; 2.8 billion mi). It is named after the Roman god of the sea and has the astronomical symbol , a stylised version of the god Neptune's trident.


History

Some of the earliest recorded observations ever made through a telescope, Galileo's drawings on 28 December 1612 and 27 January 1613 contain plotted points that match up with what is now known to be the position of Neptune. 

Source: NetGio

On both occasions, Galileo seems to have mistaken Neptune for a fixed star when it appeared close—in conjunction—to Jupiter in the night sky; hence, he is not credited with Neptune's discovery. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned retrograde that day. This apparent backward motion is created when Earth's orbit takes it past an outer planet. Because Neptune was only beginning its yearly retrograde cycle, the motion of the planet was far too slight to be detected with Galileo's small telescope. In 2009, a study suggested that Galileo was at least aware that the "star" he had observed had moved relative to the fixed stars.


Physical characteristics

  • Neptune is encircled by six rings.
  • Neptune, like Uranus, is an ice giant. It’s similar to a gas giant. It is made of a thick soup of water, ammonia, and methane flowing over a solid core about the size of Earth.
  • Neptune has a thick, windy atmosphere.

Neptune's cloud cover has an especially vivid blue tint that is partly due to an as-yet-unidentified compound and the result of the absorption of red light by methane in the planets mostly hydrogen-helium atmosphere.

Neptune


The internal structure of Neptune:
  1. Upper atmosphere, top clouds
  2. Atmosphere consisting of hydrogen, helium and methane gas
  3. Mantle consisting of water, ammonia and methane ices
  4. Core consisting of rock (silicates and nickel–iron)
Neptune's mass of 1.0243×1026 kg is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter.[d] Its gravity at 1 bar is 11.15 m/s2, 1.14 times the surface gravity of Earth, and surpassed only by Jupiter. Neptune's equatorial radius of 24,764 km is nearly four times that of Earth. Neptune, like Uranus, is an ice giant, a subclass of giant planet, because they are smaller and have higher concentrations of volatiles than Jupiter and Saturn. In the search for extrasolar planets, Neptune has been used as a metonym: discovered bodies of similar mass are often referred to as "Neptunes", just as scientists refer to various extrasolar bodies as "Jupiters".


Internal structure

Neptune's internal structure resembles that of Uranus. Its atmosphere forms about 5% to 10% of its mass and extends perhaps 10% to 20% of the way towards the core, where it reaches pressures of about 10 GPa, or about 100,000 times that of Earth's atmosphere. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere.


Atmosphere

The atmosphere is made up mostly of hydrogen, helium and methane. Very similar to Uranus, its vivid blue color is influenced by the presence of methane and some unknown factor causes the more intense color. Neptune may not be as cold as Uranus but it has the most powerful winds out of all the planets in the Solar System despite being the furthest planet from the Sun and receiving the lowest energy input from it.  At high altitudes, Neptune's atmosphere is 80% hydrogen and 19% helium. A trace amount of methane is also present.
Neptune (red arc) completes one orbit around the Sun (centre) for every 164.79 orbits of Earth. The light blue object represents Uranus.

 Prominent absorption bands of methane exist at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue, although Neptune's vivid azure differs from Uranus's milder cyan. Because Neptune's atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune's colour.


Moons

A total of 14 known moons surround Neptune. They have all been named after water deities in Greek mythology. The first moon discovered was Triton, just 17 days after Neptune itself was discovered. It is also the largest of the 14 moons. The 14 moons of Neptune can be divided into regular, irregular and unusual irregular moons. In 2013, scientists working with SETI caught sight of Neptune's "lost" moon of Naiad using data from the Hubble Space Telescope. The 62-mile-wide (100 km) moon had remained unseen since Voyager 2 discovered it in 1989.


Neptune Statistics
Discovered byJohann Gotfried Galle
Date of discoverySeptember 23, 1846
Mass (kg)1.024e+26
Mass (Earth = 1)1.7135e+01
Equatorial radius (km)24,746
Equatorial radius (Earth = 1)3.8799e+00
Mean density (gm/cm^3)1.64
Mean distance from the Sun (km)4,504,300,000
Mean distance from the Sun (Earth = 1)30.0611
Rotational period (hours)16.11
Orbital period (years)164.79
Mean orbital velocity (km/sec)5.45
Orbital eccentricity0.0097
Tilt of axis (degrees)29.56
Orbital inclination (degrees)1.774
Equatorial surface gravity (m/sec^2)11.0
Equatorial escape velocity (km/sec)23.50
Visual geometric albedo0.41
Magnitude (Vo)7.84
Mean cloud temperature-193 to -153°C
Atmospheric pressure (bars)1-3
Atmospheric composition
Hydrogen
Helium
Methane

85%
13%
2%

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