So Close, Yet So Cold!

not drawn to scale

not drawn full size

   Today, Tuesday 1 January 2013, as the Earth continues its annual trek around the Sun, the Earth reaches a point in its orbit that is called perihelion. Perihelion is the minimum distance that separates the Earth from the Sun, and we are the closest to the Sun for the year at this point in the orbit. So, at 11 p.m. CST (0500 UT 2 January) the Earth is 147,098,161 km from the Sun. Approximately one-half year or one-half revolution later, on 5 July, the Earth is at aphelion (152,097,427 km), its maximum distance from the Sun for 2013. This difference in distances is due to the shape of the Earth’s orbit being elliptical rather than circular. However the Earth has a mildly elliptically shaped orbit that is closer to being slightly out-of-round than the incorrect, very elliptical orbit that is often shown – like the illustration used here.
   To read more about the Earth’s orbit and get some teaching ideas click here to download a PDF copy of my January 2011 Scope on the Skies column Solar Explorations.

   Caveat: “The above comments are obviously northern hemisphere biased, and I make no apologies to those in the opposite hemisphere who may be sitting on a beach somewhere enjoying strawberries and cream.” He said with a big grin.
Click here to go to the Qué tal in the Current Skies web site for more observing information.

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