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nHave you ever seen those big radiontelescopes, which look like big dishes pointing up at the sky? Whatnare they listening to? Who in outer space is sending radio waves tonEarth?
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nNot so much who, as what!
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nLet’s find out how radio astronomy gotnstarted in on honor of one of its founders, Karl Jansky (born on thisnday in 1905, in the Territory of Oklahoma).
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nJansky studied physics, and he went tonwork for Bell Telephone Laboratories, where he investigated thenatmosphere and how it affects radio and telephone transmissions. innother words, he was studying what makes radio static.
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| This is a replica of Jansky’s radio telescope. |
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nHe built anlarge antenna – about 100 feet wide and 20 feet tall – and henmounted it on a turntable so he could point it in any direction. Thisnhuge antenna was sometimes called “Jansky’s merry-go-round.” Henlistened to static, and he categorized the sorts of static he heardninto several groups. One was nearby thunderstorms, one was far-awaynthunderstorms, and the last… The last was a puzzle.
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nAnd puzzles are very interesting tonscientists!
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nJansky spent over a year investigatingnthe sources of a faint, steady hiss of static. The intensity of thenhiss rose and fell once a day, so Jansky wondered if it could bencoming from the Sun. But after a few months, the most intense pointnof the static moved away from the sun. Jansky finally realized thatnthe hiss seemed to coming from the center of our galaxy – thencenter of the Milky Way.
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nJansky published his findings and gotna lot of attention for his paper. However, Bell Laboratories wouldn’tnfund Jansky following up with a larger antenna—they reassigned himnto another project—and so it was up to other scientists to developnradio astronomy further.
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nHowndoes radio astronomy work, exactly?
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nRadio waves are a kind ofnelectromagnetic radiation, like X-rays, the microwaves in ournmicrowave oven, and visible light. Radio waves have the longestnwavelengths of these.
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nStars, galaxies, black holes,nsupernovas and even the Big Bang can all be studied from the radionwaves they emit (or emitted). An “active” planet like Jupiter,nwhich has violent super-storms in the various layers of itsnatmosphere, emits radio waves, and of course our Sun emits radionwaves as well. n
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nHere’s a great source to learn aboutnradio astronomy.
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