Feb '25
Neptune is the eighth and furthest known planet from the Sun. Neptune is an ice giant, like Uranus, and was discovered on September 23, 1846 by three astronomers: John Couch Adams, Urbain Le Verrier, and Johann Galle. It was also the first planet to be calculated by mathematics and then discovered, instead of being first observed.[1]
Neptune has 16 known natural satellites. Its biggest moon is Triton and its smallest and most distant is S/2021 N 1, which also is the most distant moon in the solar system compared to that of its parent planet.[2]
Neptune is famous for having the fastest wind currents in the entire Solar System, speeding up at a velocity of 1,200 mph (1,900 kph).[1]
Neptune is home to many storms which have come and gone throughout its observational lifetime. The largest of these storms is the Great Dark Spot, which was also the first storm observed on Neptune. It has since dispersed and no longer exists.[3]
Formation
Neptune's core formed from a clump of rocky material, a planetesimal, that was around 2~5 times in Earth's mass. Its core gathered enough gas to become a Jovian, ice giant planet. It's formation may have been fuelled by other factors, however this is unconfirmed.[4]
Ever since, Neptune has been in a position where it safeguards the Kuiper Belt and resonant objects. It's mass, which is 17 Earth masses, keeps this region in check.
Migration
Main article: Migration of Neptune
The migration of Neptune refers to the process in which the planet is believed to have moved from its original position in the early solar system. According to current theories, Neptune may have formed closer to the Sun, alongside Uranus, but later migrated outward due to gravitational interactions with other objects, including the giant planets and possibly the early Kuiper Belt. This migration is thought to have played a role in the dynamical evolution of the outer solar system, including the scattering of ice giants and the formation of the Kuiper Belt. Some models suggest that Neptune's migration might have been caused by interactions with the protoplanetary disk, which could have propelled the planet outward while causing a rearrangement of smaller bodies, including the destabilization of the orbits of nearby objects. This movement likely occurred in stages, shaping the current configuration of the solar system's outermost planets and the distribution of smaller icy bodies.[4]
Composition
Neptune's atmosphere is composed of the same materials as Uranus, methane and ammonia, with small amounts of ice in its atmosphere and its core composed of mostly metallic materials and rock.[1]
Because Neptune and Uranus are so similar, they have been categorized separately. Neptune and Uranus have been categorized using the term "ice giant" due to there being an exceptional amount of cryogenic compounds of carbon and ammonia in the atmosphere, which can lead to frozen water in the atmosphere and the surface.
Internal Structure
The internal structure of Neptune is similar to that of the neighboring planet of Uranus. The first layer is the mantle, which makes up the mass of Neptune. The mantle consists of a water-ammonia compound and methane. In fact, the water-ammonia compound makes up so much of the mantle, scientists refer to it as a water-ammonia ocean. The core of Neptune is mostly made up rock silicates such as iron and nickel.[1]
Rings
Main article: Rings of Neptune
Neptune has its own collection of rings called the Rings of Neptune. These rings were discovered in the La Silla Observatory in Chile by Reinhold Häfner, Patrice Bouchet, and Jean Manfred. These rings very lowly dense. Even at their densest, they are only as dense as the lesser dense parts of Saturn's rings. The innermost moons in the rings include Despina, Naiad, Thalassa, and Galatea.[5]
Orbit and Rotation
Neptune makes only one orbit around the Sun in about 164.8 Earth years. This is because Neptune is more than three billion miles from the Sun, which is about 4.5 billion km. This makes Neptune less than double as far from the sun then Uranus.[6]
Because of its gaseous nature, Neptune's equatorial rotation is equal to 18 Earth hours, yet since the wind speeds towards the poles are faster. Its polar rotation is equal to 12 Earth hours. This makes Neptune the third fastest in terms of axial rotation.[6]
Moons
Main article: Moons of Neptune
The inner moons of Neptune. They are to scale in size to one and another, however Neptune is not to scale.
Neptune concurrently has 16 known moons. These moons are unique compared to those of other planets, as half of these moons are suspected to not have originated within orbit of Neptune.[1]
Inner Moons
Naiad, Thalassa, Despina, Galatea, Larissa, Hippocamp, and Proteus are regular inner moons, all having a synchronized orbit with Neptune's rotation.[2]
Naiad and Thalassa are very similar to one and another and are also considered to be shepherd moons of Neptune's rings, along with Despina and Galatea. Larissa is the fourth largest of the inner prograde moons and is the last of the close inner moons.
Hippocamp, which was discovered in 2004, is the smallest of the inner moons and isn't that well known compared to the others. The last of the inner moons is Proteus, the second largest moon of the planet. Its suspected that Proteus, along with Triton, originally formed in the Kuiper belt, before getting captured by Neptune during the Nice model. Ever since such, Proteus has settled into a calm orbit.[2]
Triton, the largest moon of Neptune.
Triton
Triton is the only moon that has achieved hydrostatic equilibrium and is by far the largest of the moons. Triton is well known for being the largest retrograde moon, which it orbits in the opposite direction compared to the planets rotation. Triton also outgasses and ejects ice and liquid nitrogen out into space, creating a faint tail behind it, similar to a comet. Triton and Titan are the only two moons in the solar system in which their atmospheres are thick enough for weather cycles to occur. Triton is also very cryogenic with cryovolcanoes erupting periodically. Triton is one of the only objects known to be geologically active.[7]
Outer Moons
Nereid is very similar to Proteus and may have also potentially formed in the Kuiper belt before being captured. This claim is supported by evidence, such as its orbit, which is highly elliptical compared to the inner moons and Triton. Halimede also follows a similar theme, however it is much different from Nereid.[2]
The other remaining outer moons aren't all that interesting and well known compared to the others. These outer moons are divided into 2 groups, The Sao Group, which contains Sao, Laomedeia, and S/2002 N 5, and the Neso Group, which contains Psamathe, Neso and S/2021 N 1. The latter is the furthest known moon compared to its planet discovered and takes the longest amount of time to orbit, 28 years.[1]
It is suspected that there may be even more moons of Neptune, with some estimates going as high as 50 moons. However, due to restrictions and just how far Neptune is, discovering these potential moons will take a long time.
| Moons of Neptune | |
|---|---|
| Inner | Naiad • Thalassa • Despina • Galatea • Larissa • Hippocamp • Proteus |
| Triton | Triton |
| Ungrouped | Halimede • Nereid |
| Sao Group | Sao • Laomedeia • S/2002 N 5 |
| Neso Group | Psamathe • Neso • S/2021 N 1 |
Atmosphere
A high resolution color image, taken 2 hours before Voyager 2’s closest approach, provides obvious evidence of vertical relief in Neptune's bright cloud streaks.
Most of the atmosphere of Neptune is made up of hydrogen, making up more than eighty percent of the atmosphere. The rest is made of helium, methane, hydrogen deuteride, and ethane.[1]
Great Dark Spot
The Great Dark Spot
The Great Dark Spot, is a dark spot on the surface of the planet, Neptune. This one has many similar characteristics to the more famous, and commonly mistaken for, Great Red Spot. One example of a similarity is the category of the storm, for they are both anticyclonic storms, or storms that rotate different directions than that of regular storms, which are referred to as cyclonic. The first spot was observed by the Voyager 2 probe in 1989. The interior of these spots are cloud-free compared to that of Jupiter's Great Red Spot, which densely packed with dust-filled clouds. Winds in this storm are the fastest in the Solar System, being 1500 miles per hour.[3]
Dimensions
The dimensions of the GDS were estimated by scientists in 1995. The dimensions measured were 15,900 x 9870 x 8350 x 4100 miles.
Disappearance
In November of 1994, the Hubble Space Telescope failed to photograph the GDS, leading scientists to believe that it disappeared. Many theories surround this disappearance - one such theory claiming that due to the high wind speeds of the cyclones, as well as their close proximity to one another, the storms all pushed themselves into different directions.[3]
Side view of Neptune, capturing the Great Dark Spot (center-left), Scooter (center-bottom) and the Small Dark Spot (bottom).
Small Dark Spot
The Small Dark Spot also followed a similar pattern to that of the Great Dark Spot. It was insignificant compared to other storms, but yet has been hailed because of it's appearance resembling an eye. It went on to be photographed a couple of times by Voyager 2. This storm was also given the designation "D2."[3]
However, this storm was later undetectable in the 21st century, and it likely had the same fate as the Great Dark Spot.
Scooter
Scooter is a small cyclonic storm, equal to that of a tropical storm here on Earth. This storm is likely the oldest storm we know on Neptune so far, as it sits in an area where storms don't usually form. Similar to the Small Dark Spot, Scooter went undetectable, however most scientists still think it's around. It likely only lost it's methane convection.
The Northern Great Dark Spot
After the disappearance of the main Great Dark Spot, a new, similar spot formed the northern hemisphere of Neptune. It was given the name of "Northern Great Dark Spot", or NGDS. It is the last major storm remaining, and has lasted several years.[3]
Trivia
- Neptune was actually first observed in 1612 when Galileo Galilei first spotted it with his telescope. He mistook it as a star and thought nothing of it.
- Although Neptune is the smallest of the gas giants, it is the third largest in terms of mass, nearly a third greater then Uranus.
Gallery
See Also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Neptune | Planet, Moons, Rings, Temperature, Mass, Diameter, & Facts | Britannica
- ↑ 2.0 2.1 2.2 2.3 Moons of Neptune | Table, List, Year Discovered, & Facts | Britannica
- ↑ 3.0 3.1 3.2 3.3 3.4 Hubble Tracks the Lifecycle of Giant Storms on Neptune | NASA
- ↑ 4.0 4.1 How Did Neptune Form? | Space
- ↑ Neptune's Rings | NASA Science
- ↑ 6.0 6.1 In Depth | Neptune | NASA Solar System Exploration
- ↑ In Depth | Triton | NASA Solar System Exploration
| The Planets and Dwarf Planets | |
|---|---|
| Planets | |
| Inner: (Mercury • Venus • Earth • Mars) Outer: (Jupiter • Saturn • Uranus • Neptune) | |
| Dwarf Planets (and candidates) | |
| Ceres • Pluto • Haumea • Makemake • Quaoar • Orcus • Eris • Gonggong • Sedna | |