On Tuesday, July 12, 2011, the planet Neptune will complete its first revolution around the sun since its discovery on September 23, 1846. As it takes Neptune 164.79 Earth-years to go full circle through the constellations of the Zodiac, it is only now completing its first full orbit since its detection by humans. Hence the anniversary celebration.
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.
There is much to commemorate — Neptune’s discovery marked a turning point in astronomy. Its existence was revealed, not through a serendipitous observation by an astronomer but by the careful work of mathematicians. They calculated that perturbations in the orbit of Uranus, then thought to be the sun’s most distant planet, could only be explained by the existence of another, even remoter world whose gravity was affecting Uranus’s path.
The mathematicians – Englishman John Adams and Frenchman Urbain Le Verrier – made their calculations separately. Both agreed, however, where in the sky astronomers would pinpoint the planet causing those perturbations. But they dealt with the information very differently, says historian Allan Chapman of Wadham College, Oxford.
As Neptune is too faint to be seen by the naked eye, a pair of binoculars or a telescope is needed to view this world if you know where to look. This detailed sky chart will help you to find Neptune’s place in the sky — it will be located in Aquarius, the constellation where astronomers discovered the blue planet.
Next month Neptune reaches opposition and is a decent target for observers.
Happy Birthday, Neptune! 🙂