Neptune has 13 Moons. Triton. Nereid. Naiad. Thalassa. Despina. Larissa. Proteus. and Galatea. plus five smaller. nameless Moons. Triton and Proteus orbit close to Neptune ; Nereid is in a distant orbit. Triton is the lone Moon in our Solar System with a retrograde orbit ( revolving in the opposite way than its primary. Neptune. is revolving ) . The Moon Triton is the coldest measured object in our Solar System. and Nereid is the Solar System object with the most bizarre orbit. The Moons of Neptune in order of distance from Neptune.
The first four Moons of Neptune. Naiad. Thalassa. Despina. and Galatea. are so near to Neptune that they orbit within its ring system. Small is known about them. The following one out. Larissa. was really discovered in 1981. when it blocked a star. This was attributed to the ring discharge. but subsequently was found to be the Moon. being re-discovered by Voyager 2 in 1989. Proteus is the second-largest Moon in orbit around Neptune. It is so close to the planet that Earth-bound telescopes can non see it. Triton is following ( right ) . and is one of the strangest Moons in the solar system. First. it is one of merely three Moons in the solar system that has an ambiance ( Jupiter’s Io and Saturn’s Titan are the other two ) . It is thicker than Io’s. yet much thinner than Titan’s. Its force per unit area is 1/100. 000 of Earth’s. Second. Triton has a retrograde orbit. which means that it orbits the opposite manner the planet spins. This is a really strong indicant that Triton was captured. This in itself is non unusual ; both of Mars’ Moons were captured. What is unusual is that Triton is two-thirds the size of our Moon. When two organic structures have a close brush. one does non automatically capture the other. particularly if it is so large.
One theory is that Triton must hold really hit Neptune. bounced off the ambiance. and gone into orbit because it lost all of its impulse. Another manner this could hold happened is that Triton collided with one of Neptune’s Moons. smashed it to spots ( perchance making the rings ) . and lost so much impulse that it couldn’t flight Neptune’s gravitation. Third. it is merely 38 °C ( 100 °F ) above absolute nothing ( the temperature at which all affair comes to rest ) . In such frigid a clime scientists did non anticipate to happen active geysers. But. they did. They spew out a gaseous signifier of N. which is what creates its ambiance. The 8th Moon. Nereid. has a extremely egg-shaped orbit that causes it to swing about Neptune at assorted distances. When closest. it is 1. 342. 530 kilometer ( 834. 210 stat mis ) from the planet. At the farthest distance. it is 9. 667. 120 kilometer ( 6. 006. 870 stat mis ) from Neptune. The last five Moons were discovered in the first few hebdomads of and throughout 2003. They have non yet been given official names by the International Astronomical Union. Very small is yet known about them.
The largest of the 8 Moons of Neptune. Unlike all other big planetal Moons. Triton has a retrograde orbit ( it rotates opposite to Neptune’s rotary motion ) and is in synchronal orbit. It besides has a extremely inclined axis. Triton is the coldest object that has been measured in our Solar System. with a temperature of -235° C ( -391° F ) . This bouldery Moon has a polar ice cap at its south pole and many other varied geologic characteristics including vents. immense clefts in the surface. and geysers of gaseous N. It has a really thin. hazy atmosphere ( largely nitrogen ) and a blowy surface covered with nitrogen ice. Triton is easy gyrating in towards Neptune. Nereid
Neptune’s outermost ( and third largest ) Moon is Nereid. which has an irregular form. It is the smaller of Neptune’s 2 larger Moons. It has a Very egg-shaped orbit. traveling every bit near as 867. 000 stat mis from Neptune and every bit far as 6 million stat mis from it ; it may be a captured asteroid. It takes about one Earth twelvemonth for Nereid to revolve Neptune in this utmost orbit ( 360. 1 yearss ) . Nereid’s has the most bizarre orbit in the solar system. The distance from Nereid to Neptune varies from about 1. 353. 600 kilometres ( 841. 100 stat mis ) to over seven times as far. 9. 623. 700 kilometres ( 5. 980. 200 stat mis ) .
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