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Q & A: Heat and Light in Space

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Most recent answer: 02/20/2011
Q:
If all the earths heat and light come from the sun(presumably traveling from there to here),then why are the 93 million miles between earth and sun devoid of heat and light?
- Jim (age 54)
elmhurst, il usa
A:
Jim,

It's actually not at all devoid of light. Any object that happens to pass through there (a comet, for example) gets visibly lit up by the light coming from the sun.

The heat flow is just the same thing as the light flow, but also counting the parts of the light (infrared and ultraviolet) that aren't visible to us. Any object in that space will be heated by the sunlight hitting it.

The reason that the space mostly looks dark to us is just that there aren't many things in it for the light to bounce off of. So the light just keeps going rather than bouncing toward our eyes. Of course the part of the light that happened to be heading toward us to begin with keeps heading toward us- that's the part we see as the sun.

-Zach +mbw

(published on 02/20/2011)

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