By Chris Fellows, Serenity Mobile Observatory
This week I am highlighting another very interesting astronomically related destination, the Very Large Array (VLA). Run by the National Radio Astronomy Observatory (NRAO), the facility is located on The Plains of San Agustin, Old Hwy 60, Magdalena, NM 87825 (GPS coordinates 34 04’43.497N, 107 37’05.819W). This iconic telescope was made famous in the American lexicon by its inclusion in the 1997 summer blockbuster “Contact,” starring Jodie Foster.
This massive facility consists of 27 radio antennas in a Y-shaped configuration. Each antenna is 25 meters (82 feet) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna 36km (22 miles) across, with the sensitivity of a dish 130 meters (422 feet) in diameter.
Radio telescopes were developed to address a specific problem: The human eye can detect only a very narrow slice of the electromagnetic spectrum called visible light. As you can see in the above diagram, visible light is just the tip of the iceberg when it comes to information streaming onto Earth from every direction. Scientists have also developed telescopes to detect the infrared, x-ray, and even gamma ray portions of the spectrum. In fact, the new James Webb space telescope planned to launch sometime in 2019, will look at the universe in the infrared domain.
In 1886, scientist Heinrich Hertz proved that he could generate and receive a kind of invisible light in wavelengths longer (well below) infrared wavelengths – these became known as Hertzian Waves. Today, we call these waves “radio waves” and it’s what your radio receiver in your car or RV pick up to listen to the news or your favorite music programs.
Radio telescopes like the VLA have a distinct advantage over visible light telescopes: They can be used 24 hours a day regardless of weather conditions, clouds are not a problem and neither is daylight. Many new discoveries have been made by radio telescopes: These include the true rotation of the planet Mercury, imaging of asteroids, the discovery of binary pulsars, and millisecond pulsars, or stars that rotate at hundreds of times per second. The fastest rotating pulsar known is PSR J1748-2446ad at 716 Hz, or 716 times a second.
The VLA hosts guided tours on the first Saturday of each month at 11 a.m., 1 p.m., and 3 p.m. No reservations are required – simply show up at the VLA Visitor Center 15 or so minutes before the desired tour time. These tours last 45 minutes and take visitors to areas behind the scenes at the VLA.
The VLA Visitor Center is open every day from 8:30 a.m. through sunset. As you enter, a sign will point you toward the theater, a good place to begin your tour. Here a 20-minute video presentation, produced in 2013 and narrated by Jodie Foster, provides good overview of radio astronomy, interferometry, and the VLA itself.
There is also a self-guided walking tour of the facility. I especially enjoyed this. You can walk among the dishes themselves – the only way, in my opinion, to get a feel for the size and scope of the telescope. If you look very closely you can see me standing at the base of the massive dish in the photo. The walking tour will take you through the Radio Sundial, past the Whisper Dish Gallery, on to the Radio Astronomy Gallery, and finally to the base of one of the 230-ton working antenna on the array (pictured above). From there you can head to the control building and climb a bunch of stairs up to the observation deck for a view of the entire array. The walk ends back at the Visitor Center and gift shop, where you can pick up souvenirs. The gift shop is open every day at 9:00 a.m. until 4:00 p.m.
If you are in the area, or just driving through, I highly recommend that you plan a stop at the VLA. It is a fascinating device that your tax dollars paid for and has discovered many interesting and illuminating things about our universe. Also remember, this is a radio telescope, so while you are there, please turn off your cell phone or put it in airplane mode. This telescope is picking up the faintest of signals from billions of lightyears away, and your cell phone can destroy valuable data if you don’t turn it off!
Chris Fellows, Serenity Mobile Observatory
Find Chris on Facebook (or, if you’re lucky, at your campground). (Editor: Check out his amazing photos on his Facebook page!)