Back in August 2006, Pluto was considered the farthest planet from the sun and then the International Astronomical Union (IAU) downgraded the status of Pluto to that of “dwarf planet.” Till 2006 people thought the farthest planet was Pluto. Now research says that Pluto and Neptune swap places every 248 years. This means that for a short period of time Neptune becomes the farthest planet.
The Cosmic Dance –
You must be wondering how the heck is that possible! In the time span of 1979-1999, the farthest planet was Neptune. Once you go far far away from Sun things there are on a much slower scale. Think of it this way. Pluto was discovered in 1930, and it had its planet status revoked in 2006. In the 76 years between those two dates, it had only covered about three-tenths of its orbit around the sun. It won’t be until 2178 that it will complete its first full “year” since its discovery.
Because of Pluto’s extremely elliptical orbit, it comes closer to the sun than its nearest neighbor, Neptune. It’s all about the perihelions. Perihelion is the point at which an object is closest to the sun while the aphelion is the point at which it is farthest. Both aphelion and perihelion are measured in AU (Astronomical Unit – it is the average distance between Earth and the Sun which is approximately 150 million kilometers or 93 million miles). The Earth’s perihelion position is 0.98 AU and aphelion position is 1.01 AU thanks to our nearly circular orbit. But since Pluto’s orbit is so elliptical, its perihelion is much, much, much closer to the sun than its aphelion. At the farthest point, it’s 49.5 AU away (in other words, almost 50 times farther from the sun than the Earth is), but it swings up to 29.7 AU at its closest. By contrast, Neptune’s orbit is almost as circular as Earth’s, ranging from 30.4 AU to 29.8 AU. That means that every single time Pluto makes an orbit of 240 years, its closest point comes in 0.1 AU (9.3 million miles, or 15 million kilometers) closer than the ice giant next door.
Other Strange Facts About Pluto –
The orbit of all other planets is nearly flat. But orbit of Pluto is inclined at an angle of 17°. Consider an imaginary plane paper on which all the other planets lie along with the sun but Pluto is inclined to that paper at 17°. In other words, if you look the paper from the side you will see pluto elevated by a certain distance. Moreover, the planet is so small that Neptune has a significant effect on its motion. Recently New Horizons spacecraft did a detailed study about the terrain and other properties of this dwarf planet. It also sent us pictures of it.