On Tuesday, July 12, 2011, the planet Neptune completes its first revolution around the sun since we earthlings discovered it on September 23, 1846. Neptune reaches this milestone at 22:27 Universal Time (UTC) today.
Woot woot! Best images for celebrating Neptune
It takes Neptune 164.79 Earth-years to go full circle through the constellations of the Zodiac, whereas the Earth goes full circle in just 365.256 days. Or you could say that a year on Neptune lasts about 165 years, in contrast to a year on Earth of about 365 days.
How do I translate Universal Time into my time?
Neptune, the 8th planet outward from the sun, is presently the most distant planet in the solar system. That’s because the International Astronomical Union reclassified Pluto as a “dwarf planet” in 2006. By the way, Neptune circles the sun three times for every two times that Pluto does.
We saw an article recently saying Neptune would be visible to the eye around now. Not so. Neptune is the only solar system planet that you absolutely cannot see without optics (Uranus, the 7th planet outward, is faintly visible to the unadided eye on a clear, dark night). You can see Neptune with good binoculars or a telescope, but you need to know right where to look. During June/July/August 2011, you have to stay up late or wake up early to see this world. What’s more, you’ll definitely need a detailed sky chart to find Neptune’s place in the sky.
Familiar with the bright star Fomalhaut or the constellation Aquarius? If so, you can try to star-hop to Neptune. Our sky chart also points out the star Skat (Delta Aquarii), the radiant point for the upcoming Delta Aquarid meteor shower, which peaks in late July.
EarthSky’s meteor shower guide for 2011
John Couch Adams
Neptune’s discovery story is wonderful. It was 1846, a time when exciting new worlds were being found, a time much like our own time, albeit the discoveries came at a much slower pace than now. William Herschel had discovered the planet Uranus in 1781. By 1846, astronomers had noticed irregularities in the path of Uranus around the sun, which could not be entirely explained by Newton’s law of gravitation. These irregularities could, however, be resolved if the gravity of a more distant planet were disturbing Uranus’ orbital path.
Urbain LeVerrier
In 1845, French astronomer Urbain Le Verrier in Paris and British astronomer John Couch Adams in Cambridge separately and both successfully calculated the position of this unknown planet. On the early morning of September 24 – at the Berlin Observatory – astronomer Johann Gottfried Galle found Neptune, working from Le Verrier’s calculations. Can you imagine the sensation? It was a dramatic confirmation of Newtonian gravitational theory.
Le Verrier at first got credit for the discovery. He was said to have discovered the planet “with the point of his pen.” The Royal Society awarded Le Verrier the Copley medal in 1846 for his achievement, without mention of Adams. Nowadays, though, you always hear of John Couch Adams’ contribution to Neptune’s discovery. Yay history!
Fast forward to our time – today, July 12, 2011 – with the planet Neptune now having completed one revolution around the sun, the first completely known revolution since its discovery. It’s an anniversary, or a birthday of sorts, for Neptune – important only to humans, of course. Still, you can wish Neptune happy birthday today as it finishes up its first trip around the sun, as known by us earthlings!
Clocking Neptune’s mysterious spin
How was Pluto discovered?
July 2011 guide to the five visible planets
