Neptune

Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It 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. The planet orbits the Sun once every 164.8 years at an average distance of 30.1 AU. It is named after the Roman god of the sea and has the astronomical symbol, representing Neptune's trident. A second symbol, an L-V monogram for 'Le Verrier', analogous to the H monogram for Uranus, was never much used outside of France and is now archaic. Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation.

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Uranus and Neptune May Have Been Cosmic Strangers All Along, New Research Reveals

Queen's University Belfast Students Find Neptune's Elusive Trojan Asteroids

Jupiter, Saturn, Uranus and Neptune could destroy each other sooner than we thought, simulations hint

Rubin Observatory reveals its first dwarf planet candidate in our solar system; among the largest dwarf planet candidates ever discovered beyond Neptune

Astronomers found a mysterious object beyond Neptune, and it could be a new dwarf planet

A modern dynamo at Triton as a consequence of its capture by Neptune

Uranus and Neptune May Have Taken Different Paths to Becoming Ice Giants

SwRI staff contribute to new ideas about origins of Uranus, Neptune

Planetary 'twins' Uranus and Neptune may have different origin stories

SwRI staff contribute to new ideas about origins of Uranus, Neptune. New study suggests Neptune’s building blocks originated far from its cosmic neighborhood...

Following Neptune Through Opposition 2026

Astronomers Expected More Tiny Worlds Beyond Neptune – Webb Found Something Else

James Webb Space Telescope and Hubble discover 27 puzzling new objects orbiting the sun far beyond Neptune

A Cosmic Catastrophe May Have Turned Neptune’s Ancient Moons Inside Out

Scientists Made Ice Stay Solid Above 2,000°C. The 'Superionic Ice' Could Be Found Inside Uranus and Neptune: The researchers squeezed water to millions of atmospheres and discovered a bizarre new form of ice

Hubble and Webb Team Up to Spy Tiny Frozen Worlds beyond Neptune

Scientists crushed diamond beyond Neptune-like pressures—and solved a 20-year mystery

Neptune’s tiny moons may be the wreckage of shattered ancient worlds

Webb telescope finds signs of ancient disaster for Neptune's moons

3 moons of Neptune may be remnants of ice worlds shattered in a catastrophic crash