When I first moved to New Mexico about 1970, the one road that always made me wish I was somewhere else was US 60 between Magdalena and Datil. The fearsome Plains of San Agustín seemed to go on forever with no turns, hills, trees, or even other cars to break up the long crossing of 30 miles. It felt like I had glimpsed infinite space...and it was boring! Later, I came to appreciate the vast horizons found in so much of New Mexico.
The emptiness of the Plains of San Agustín, however, was not to last. Work on a huge radio telescope began right in the middle of all that nothingness in the 1970’s, and by 1981 the entire Very Large Array was completed. The ride along US 60 hasn’t been the same since.
The VLA is a radio astronomy observatory consisting of 27 dishes spread out on railroad tracks shaped in a giant “Y.” Each dish is 82 feet across, 90 feet high, and weighs over 200 tons. When the dishes are stretched out to their maximum distance it makes for a radio telescope over 22 miles in diameter. And yet this astounding sight seems but a few white dots on the vast Plains of San Agustín.
Radio telescopes are a bit different from optical telescopes. Although both visible light and radio waves are part of the electromagnetic radiation spectrum, human sight can detect wavelengths from about 400 to 700 billionths of a meter. However a single radio wave can be as long as a football field. The VLA collects radio waves from about 7mm to 4 meters. That is why the array is so large: the waves themselves are large.
Radio waves can pierce through clouds. For example, although clouds can obstruct our sight completely, radios still work whether its cloudy or not. This feature allows a radio telescope to see through the dusty clouds in the center of the galaxy and come up with those amazing pictures.
The VLA was upgraded a few years ago and renamed in honor of the young physicist Karl G. Jansky, who in 1933 announced that radio waves were coming from deep space. Thus radio astronomy was born.
The Karl G. Jansky Very Large Array is open daily from 8:30 AM until sunset. Highlights include a feature-filled self-guided walking tour and a gift shop. Guided tours are offered the first Saturday of each month.