Neptune is the windiest planet in our solar system, causing gust winds that can reach over 1,200 miles per hour. This soothing extension of the sapphire reveals some of the circular mess below in huge swirls that look like dark smudges on its surface. Neptune, orbiting about 2.8 billion miles from the Sun, is the most distant planet discovered so far in our solar system (that is, after Pluto was reclassified as a dwarf planet in 2006). Neptune rotates rapidly compared to Earth, taking 16 Earth hours one day. But its great distance from the Sun means that the years are long, and it takes 165 Earth years to make one trip around our glowing star.

At this distance from Earth, Neptune is the only planet in the Solar System that cannot be seen in the night sky without a telescope. Even neighboring Uranus, though faint, shines in the clear night sky. This means that Neptune was not easy to spot. Some suggest that Galileo Galilei first discovered Neptune as early as 1613. Many believe that he mistook it for a star at the time, yet some scholars think that may not be the case. Most of the discovery of Neptune is attributed to a mastery of mathematics in the nineteenth century. After Uranus was discovered at the turn of the century, astronomers noticed that it appeared to be affected by a strange gravitational experiment. This oddity prompted British mathematician John Cush Adams to calculate Neptune's possible position in the 1840s. Two years later, the French astronomer Urban Le Verrier did the same.

Neptune is one of two ice giants in our cosmic family, along with Uranus. It is covered in an atmosphere of hydrogen and helium, with traces of methane, water and ammonia. Under the primary hail layer, temperatures and pressures increase rapidly. Deep in Neptune below its cloud peaks, it may have a vast, hot ocean of water enveloping its rocky core. But not all scientists agree that the planet is cool enough that this liquid would still exist without evaporating. The methane in the atmosphere reflects blue light, painting the world in vibrant colors. In most images, Neptune appears to be a deeper and brighter blue than Uranus, which appears as a pale turquoise point. But Neptune is likely just as pale as its neighbor and appears darker in images due to its greater distance from the sun. However, according to NASA, there may be another unknown element in Neptune's atmosphere that colors the world slightly differently.

Neptune has 14 known moons as of 2019. Its largest celestial moon, Triton, is the only large moon in the Solar System that has a retrograde orbit, which means that it blasts around Neptune in the opposite direction of the rotation of the host planet. This strange orbital direction may be evidence that it wasn't always a moon. There are five known rings of rock and dust surrounding Neptune - all named after astronomers who helped shed light on details about the windy world. The names of the episodes are Galle, Le Verrier, Lassell, Arago, and Adams. Neptune also contains several partial rings, known as arcs.

Only one spacecraft visited the dark blue world. Voyager 2 got flogged in 1989, collecting captivating data and photos. Although many scientists have suggested additional visits, none of them have yet been approved. Until another plan for visiting Neptune is put in place, researchers will have to satisfy their curiosity from afar, making use of observations from the Hubble Space Telescope as well as telescopes whose bases are firmly anchored to Earth.

Neptune was not known to the ancients.
It is invisible to the naked eye and was first observed in 1846. Its location was determined using mathematical predictions. Named after the Roman god of the sea. Neptune's radius is 15,299.4 miles (24,622 kilometers), which is about four times larger than Earth's. If the Earth were the size of a nickel, then Neptune would be the size of a baseball. At an average distance of 2.8 billion miles (4.5 billion km), Neptune is 30 AU from the Sun. One of the astronomical units (abbreviated as AU) is the distance from the Sun to Earth. From this distance, it takes 4 hours for sunlight to travel from the Sun to Neptune.

Neptune was formed when the rest of the solar system formed about 4.5 billion years ago, when gravity pulled the coiled gas and dust inwards to become this ice giant. Like its neighbor Uranus, Neptune was likely closer to the Sun and moved to the outer Solar System about 4 billion years ago. Neptune does not have a solid surface. Its atmosphere (composed mostly of hydrogen, helium, and methane) extends considerably deep, gradually incorporating into water and other melted ice over a heavier solid core with roughly the mass of the Earth.

The main axis of Neptune's magnetic field is tilted about 47 degrees compared to the axis of the planet's rotation. Like Uranus, whose magnetic axis is tilted about 60 degrees from the axis of rotation, Neptune's magnetosphere undergoes wild changes during each cycle due to this misalignment. Neptune's magnetic field is about 27 times stronger than Earth's. Neptune's environment is not conducive to life as we know it. The temperatures, pressures and materials that characterize this planet are likely to be so intense and volatile that organisms cannot adapt to them.