How Long Does It Take Neptune To Orbit The Sun?
QUICK ANSWER
A year on Neptune takes about 165 Earth years, or roughly 60,190 Earth days. Neptune completed its first full orbit since being discovered in 2011, exactly 165 years after Johann Galle first spotted it in 1846. A day on Neptune is much shorter, just about 16 hours long.
Neptune takes 165 Earth years to circle the Sun once. The planet was discovered in 1846 and didn't complete its first full orbit since then until 2011. No human lifetime is long enough to see Neptune complete more than half of one trip around the Sun. The long year combined with a short day creates one of the strangest timekeeping situations in the solar system.
How long is a year on Neptune?
About 165 Earth years, or 60,190 Earth days. According to NASA, Neptune's orbital period is the longest of any planet in our solar system. Neptune moves slowly through its orbit, about 12,200 mph, the slowest orbital speed of any planet. The combination of huge orbital distance and slow movement means Neptune takes nearly two human lifetimes to complete one trip around the Sun. Neptune's slow orbit is part of why it was so difficult to detect from Earth before telescopes became powerful enough.
Has Neptune completed an orbit since its discovery?
Just one, in 2011. Neptune was discovered on September 23, 1846, and completed its first observed full orbit around the Sun 165 years later on July 12, 2011. The anniversary was celebrated by astronomers worldwide, with NASA and the Hubble Space Telescope releasing detailed new images of the planet. Neptune is currently working through its second observed orbit and won't complete another one until around 2176. Most people alive today won't be around for the next anniversary.
How long is a day on Neptune?
About 16 hours and 6 minutes. Despite being the farthest planet, Neptune rotates fairly quickly compared to Earth. The relatively short day combined with the extremely long year creates a strange ratio: Neptune has about 89,600 of its own days in each Neptune year. Determining Neptune's exact rotation period was tricky for a long time because the planet is a gas giant with no solid surface to track, but modern measurements from Voyager 2's flyby and follow-up Hubble observations have nailed down the number.
Does Neptune have seasons?
Yes, but they're enormous. Neptune's axial tilt is about 28.3 degrees, similar to Earth's and Mars's. So Neptune has seasons in principle, with the hemispheres tilting toward and away from the Sun across the orbit. The catch is that each season lasts about 41 Earth years because of Neptune's 165-year orbit. Recent observations have detected real seasonal changes on Neptune, including shifts in atmospheric temperature and brightness patterns, though the effects are subtle because Neptune is so far from the Sun that solar heating barely matters.
Neptune takes 165 Earth years to complete one trip around the Sun, the longest year of any planet. The 16-hour day means Neptune has thousands of its short days in each enormous year. Neptune has completed only one full orbit since humans discovered it, in 2011, and the next one won't finish until 2176. Most of us will never see Neptune complete another orbit.
More Neptune Questions
Mystery Question?
Mystery Question?
Mystery Question?