19 March 2010


This APOD image of the solar corona (the sun's outer atmosphere), revealed during a total solar eclipse, blows me away when you consider the astronomical distances you're seeing. To help, recall that you would have to line up 109 Earths in a row to equal the diameter of the sun. Go ahead, try to wrap your imagination around that. I dare you.
It's like realizing that a photon of light, traveling at a speed of around 186,000 miles per second, can circle the Earth 7.75 times in one second, and yet takes over eight minutes to travel the nearly 93 million miles between sun and Earth.
That 93,000,000 mile distance turns out to be something of a magical balance, given the size and temperature of our sun. If Earth orbited much closer, it would resemble the noxious hothouse planet Venus. Much farther, and we would be living (or not) on a sterile, cold planet much like Mars. The conditions for life as we know it are ideal in this, our home orbit. Tomorrow, the first day of Spring, might be a good time to silently appreciate that fortuitous arrangement.

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