Perihelion!

Contributed by
Jan 2, 2010
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Does the Sun look a little brighter to you? Maybe that's because at nine minutes after midnight (UT) tonight, January 2/3, the Earth will be at perihelion, the closest point on its elliptical orbit to the Sun.

At that moment, the Sun's center will be 147,098,040 kilometers away from the Earth's center (that's 91,402,484.5 miles for you Murricans). That is, assuming the distance from the centers of the two bodies is 0.983289667 Astronomical Units, and one AU is 149,597,870.7 kilometers. You can compare that to when we reach aphelion, our most distant point from the Sun, which in 2010 will occur on July 6 at 11:30 UT, when we'll be 1.016701958 AU or 152,096,448 km (94,508,351.3 miles) from our star.

That change in distance -- about 5 million kilometers, or 3 million miles -- is only a small fraction of our distance from the Sun, so it doesn't change the Earth's temperature very much: a few degrees Celsius, but that's about it. So, of course, that's not the reason we have seasons. If it were, then we'd have winter in July in the northern hemisphere! But of course, the international cabal of astronomers covers this fact up.

Still, when you think about it, the Sun is a frakkin' long way off. Even now, at our closest point, it would take over 20 years to fly to the Sun in an airplane at 800 kph (500 mph)! And the TSA would make you sit silently with nothing in your lap for the last 3 years of the journey, too.

But my point is (in case you were wondering if I had one) that the Sun is hot, and there's a lot of it. I'm glad it's so far away, even when it's at its closest.