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The Very Large Array, one of the worlds premier astronomical radio observatories, consists of 27 radio antennas in a Y-shaped configuration 50 miles west of Socorro, New Mexico. Each antenna is 82 feet (25 m) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna 22 miles (36 km) across. Image courtesy of NRAO/AUI and NRAO

Thanks to Channel 37, radio astronomers keep tabs on everything from the Sun to pulsars to the lonely spaces between the stars. This particular frequency, squarely in the middle of theUHF TVbroadcast band, has been reserved for radio astronomy since 1963, when astronomers successfully lobbied the FCC to keep it TV-free. Back then UHF TV stations were few and far between. Now there are hundreds, and Im sure a few would love to soak up that last sliver ofspectrum. Sorry Charley, the moratorium is still in effect to this day. Not only that, but its observed in most countries across the world.

Channel 37, a slice of the radio spectrum from 608 and 614 Megahertz (MHz) reserved for radio astronomy, sits in the middle of the UHF TV band. Click to see the full spectrum. Credit: US Dept. of Commerce

So whats so important about Channel 37? Well, its smack in the middle of two other important bands already allocated to radio astronomy 410 Megahertz (MHz) and 1.4 Gigahertz (Gz). Without it, radio astronomers would lose a key window in an otherwise continuous radio view of the sky. Imagine a 3-panel bay window with the middle pane painted black. Who wants THAT?

The visible colors, infrared, radio, X-rays and gamma rays are all forms of light and comprise the electromagnetic spectrum. Here you can compare their wavelengths with familiar objects and see how their frequencies (bottom numbers) increase with decreasing wavelength. Credit: ESA

Channel 37 occupies a band spanning from 608-614 MHz. A word about Hertz. Radio waves are a form of light just like the colors we see in the rainbow or the X-rays doctors use to probe our bones. Only difference is, our eyes arent sensitive to them. But we can build instruments like X-ray machines and radio telescopes to see them for us.

Diagram showing what how Earths atmosphere allows visible light, a portion of infrared and radio light to reach the ground from outer space but filters shorter-wavelength, more dangerous forms of light like X-rays and gamma rays. To study the cosmos in these varieties of light, orbiting telescopes are required.

Every color of light has a characteristicwavelengthandfrequency. Wavelength is the distance between successive crests in a light wave which you can visualize as a wave moving across a pond. Waves of visible light range fromone-millionth to one-billionth of a meter, comparable to the size of a virus or DNA molecule.

X-rays crests are jammed together even more tightly one X-ray is only as big as an small atom. Radio waves fill out the opposite end of the spectrum with wavelengths ranging from baseball-sized to more than 600 miles (1000 km) long.

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The Curious Channel 37 — Must-see TV For Radio Astronomy