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Photons: They Ain't Just for Torpedoes
Science >
We all know that being out in the sun can make you hot. But did you ever wonder why? Summer is a good time to shed some light on the question. Let's follow the life of a packet of energy from the time it is created in our star to the time it crash lands on you as you relax at the beach.
Of course, our journey begins deep in the core of the sun. There is a lot of hydrogen there, with some helium mixed in. As you know, hydrogen is the smallest of the elements with a nucleus made up of only one tiny proton.
Now these little guys are under intense pressure, what with the whole weight of the sun over them. Consequently, they are crammed together real well. But they are also at extreme temperatures, in the tens of millions of degrees. In science that means they are moving really, really, really fast.
Through a set of events more detailed than we can cover here, the tiny, close, quick, positively charged hydrogen nuclei are actually so close and so quick that they can stick together! They form helium, next in line on the Periodic Table. This is the fusion process.
Fusion puts things together --- that's important. But along the way some of the mass gets lost. That's very important. Where did it go? It became energy!
In the sun, 600 million tons of hydrogen are fused each second! But only 596 million tons of helium get produced. The four million "missing" tons are converted into innumerable packets of energy called photons: photons on a mission, photons that need to get out.
A newly formed photon races about in a random way inside the sun, bashing into elements, being absorbed and re-emitted over and over again, and losing some of its energy along the way.
Eventually, after several million years (yes, million!) of high-energy pinball, our photon makes it to what is often called the "surface" of the sun, but which is known to astronomers as the photosphere.
This is the layer of the sun that is finally thin enough that the tiny photon actually has a chance of hitting nothing and --- kaboom zaloom --- it's gone!
Our tiny quantum of energy now speeds at over 186,000 miles a second completely by chance in the direction of that third rock from the sun, Earth.
After only two-and-a-half minutes our photon speeds by the orbit of Mercury. In just another three-and-a-half minutes, Venus' orbit whizzes by.
Finally, after millions of years of bouncing around inside the sun, and only 8 minutes and 20 seconds of spaceflight, our photon zips through Earth's atmosphere on a collision course for that beach and --- ka-blam! --- it's annihilated on your skin, transferring its energy into your body, causing you to say, "Sheesh, it's hot out here!"
Now this one little photon doesn't add up to much, to be sure, but multiply that by hundreds of billions and things can get toasty warm.
In fact you can get an idea of how much energy is flowing down on us by doing the classic magnifying glass procedure. Taking the photons that flow through just that couple of inches of glass and focusing them to a point, one can start a fire! And those are just the photons traveling through that tiny opening. Your body collects considerably more energy than that each second, which is why you have been designed with a great, if sometimes embarrassing cooling system, perspiration.
Until next time, clear skies and stay cool!
Questions or comments? Mark Ritter can be reached here.
Posted by Administrator at 2002.07.20 02:44 PM | Comments (0)
