Neptune is the farthest planet in our solar system from the Sun and has the third largest mass. It is the second of the ice giant planets, named after the Roman god of the sea. It was the first planet not to be discovered empirically.
Neptune is the eighth and the farthest planet from the Sun. It takes Neptune 165 Earth years to orbit the Sun once. Neptune has only just completed one orbit since it was discovered. The outer parts of Neptune’s atmosphere are extremely cold, -235°C (-391°F), due to its distance from the Sun. Even though it receives a low amount of energy from the Sun, compared to other planets which are closer to our star, it has the highest winds. With the discovery of Pluto in 1930, Neptune became the second farthest planet from the Sun. In 2006 Pluto was recategorized as a dwarf planet, meaning Neptune could take its title as the farthest planet from the Sun again.
Neptune is the second planet (the first is Uranus) of the ice giants. Its composition is similar to Uranus. It is believed that both Uranus and Neptune get their blue color from methane in the upper atmosphere. Neptune, however, is a much deeper blue and scientists are unsure as to what else could be in the atmosphere to cause this difference in color.
Neptune is invisible to the naked eye; it can only be viewed using a telescope. It was first discovered at the Berlin Observatory in 1846 after mathematical prediction. This makes it the only planet not discovered empirically. Galileo had observed it in 1612 but had incorrectly identified it as a fixed star. The planet is named after the Roman god of the sea.
In 1989 Voyager 2 made its closest flyby of the planet. Its detailed observations helped measure the mass of the planet, which was calculated to be 0.5% less than previously predicted.