Radiation

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3 If Earth were completely blanketed with clouds and we couldn't see the sky, could we learn about the realm beyond the clouds? What forms of radiation might be received?

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Hello again Dyonna,

If the earth was perpetually covered with the clouds you see on any overcast day when no shadows are being cast, portions of the electromagnetic spectrum would be blocked. Our first disadvantage would be that the lack of visual data from the sky for the range of vision of the human eye. For example, the sun and the moon might still be visible occasionally thought the clouds, but the planets and stars and deep space objects would not have any visible wavelengths reaching the surface. We would still have fair to excellent views of our universe in other wavelengths. Ultraviolet light, microwaves and radio waves would be less affected, sometimes not at all. So we wouldn't be totally blind. We could still form a good picture of what our universe looks like beyond the clouds.

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What do radio waves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays have in common? How do they differ?

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Hi Dyonna, You've just named off all the forms of radiation on the electromagnetic spectrum. All of those are massless photons traveling at light speed through a vacuum (186,000 miles per second). The only difference is their wavelength/frequency. (Wavelength is the reciprocal of the frequency). The radio photons have very long wavelengths (low frequencies) and the gamma rays have very short wavelengths (high frequencies). Radio photons from space can't hurt your skin, but the very short wavelengths are very harmful to carbon-based lifeforms...so you want to avoid UV, X-rays, and gamma radiation photons. Fortunately our atmosphere blocks all X-ray and gamma rays coming from the sun (by absorption collisions with the air), and most of the UV. But it's transparent to visible light, infrared (fancy name for heat), and radio photons. So that's the only difference, the wavelength of the photon. (Read that - long wavelenth is low energy photons and short wavelength is very high energy photons, so the gamma ray has the highest energy level for a photon). Hope this helps, Clear Skies, Tom Whiting Erie, PA

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What is diffraction, and how does it relate to the behavior of light as a wave?

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Hi Dyonna, You can do 3 things with light....reflect it, refract (bend) it, or diffract (split) it. One can reflect light with a mirror. One can bend light by passing it through a lens. One can split light by passing it through either a prism or a multi-slit device called a grating. (small slits, like 10,000 lines per inch). When one does the latter, passes light through a grating, and assuming light is a wave function, then behind the slit you'll see beam lines of interference and combining...light bands, dark bands, a light band, a dark band, and so on. This shows that light both interferes (cancels) like waves and combines to form a brighter bright line wave, alternatively...just like waves on the ocean do. Hope this helps, Clear Skies, Tom Whiting Erie, PA

FOLLOW UP: But at other times and other experiments, light also acts like a particle too. So today we just accept the fact that light (all those massless photons) have a dual nature... sometimes they act like particles, and sometimes they act like wave forms. They can do both. Tom