Happy Perihelion

Today, 3 January 2008, is Perihelion. Perihelion is the day the earth is closest to the sun.

Here’s an explanation, I found here <link>:

“All of the planets in our Solar System move around the Sun in elliptical orbits. An ellipse is a shape that can be thought of as a “stretched out” circle or an oval. The Sun is not at the center of the ellipse, as it would be if the orbit were circular. Instead, the Sun is at one of two points called “foci” (which is the plural form of “focus”) that are offset from the center. This means that each planet moves closer towards and further away from the Sun during the course of each orbit. The point in the orbit where the planet is closest to the Sun is called “perihelion”. The point where the planet is furthest from the Sun is called “aphelion”.

Earth reaches perihelion in early January each year, and passes through its aphelion point near the start of July. At perihelion, our planet is about 147 million km (91 million miles) from the Sun; it moves outward to around 152 million km (95 million miles) from the Sun at aphelion. Earth is about 3% further from the Sun at aphelion than it is at perihelion.”

Given the cold weather we’re having, mid-winter and all that, this sentence rang true… 

 “Some people have the mistaken impression that our seasons are caused by changes in Earth’s distance from the Sun, but this is not the case. Notice how Earth is actually closest to the Sun in the middle of the Northern Hemisphere’s winter!”


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