Neptune is a distant planet from the sun and one of our solar system’s two “ice giants.” The cold, blue world is about 30 times away from the sun than Earth and takes roughly 165 Earth years to complete a solitary orbit around our star. Neptune swirls around its axis quicker than Earth, so a day on Neptune is just around 16 Earth hours.
Scientists found Neptune in 1846 after they administered orbit analyses for Uranus that implied there was a different planet affecting Uranus’s gravity, according to the Natural History Museum in London, U.K. Neptune isn’t obvious to the naked eye, but the experimenters were able to corroborate the planet’s life using a telescope. According to NASA, astronomers had previously spotted Neptune through telescopes as early as 1612 but hadn’t stipulated it as a planet.
Neptune is the eighth planet from the sun, and the final planet in the solar system after scientists downgraded Pluto from full planetary stature to a dwarf planet in 2006. Neptune is the farthest planet in the solar system from Earth and orbits at a length of between 2.7 billion miles and 2.9 billion miles from our world, depending on where the two planets are in their orbits, Live Science’s sister site Space.com previously reported.
According to NASA’s Jet Propulsion Laboratory, the Voyager 2 probe took 12 years to reach Neptune (opens in new tab). However, the probe traveled at an average speed of 42,000 mph — much faster than humans have ever traveled.
“The extra heat source on Neptune [and Jupiter and Saturn] is largely due to gravitational contraction,” Joshua Tollefson, a data scientist formerly at California, Berkeley, told All About Space magazine. “As the planet slowly gravitationally contracts, the material falling inward changes its potential energy into thermal energy, which is then released upwards out of the planet.”