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| http://scienceblogs.com/startswithabang/2009/08/26/why-our-analemma-looks-like-a/ |
You see, the Earth's orbit is not perfectly circular. It's an oval. When Earth comes closest to the sun, it is at what is called perihelion. Planets with more ovular orbits around the sun, have a closer perihelion. The same goes for their aphelion, which is when they are farthest from the sun.
The dwarf planet Eres has such a contrasting perihelion and aphelion that when it goes farthest away from the sun, its atmosphere freezes. When it reaches perihelion, its atmosphere melts and falls to the surface.
This concept is not exempted from the AstroShire County. When you look at the interactive map of a planet, its orbit is at median, meaning that it is only its mean distance from the sun. When Saturn is at perihelion, which is 9 miles from Greylock, it passes through Ioka Valley Farm. However, when Saturn is at aphelion, which is 10.01 miles, it passes through the Berkshire Mall. At median, Saturn will pass through Friendly Fred's.
Aphelion and perihelion aren't too hard to understand. It's very helpful to know!
