Question: I just toured the VLA today with a friend (both of us are engineers) and both of us were wondering how radio telescopes work. We’re curious at the 25-words-or-less level, as opposed to a deep and full understanding.
Cameras capture visible light, a certain area of sky, on film or a CCD chip. In other words, a lot of pixels are captured at once.
Radio telescopes, I would think, would capture only one pixel at only one frequency (per antenna). To get a second pixel, wouldn’t you have to move the antenna slightly? How do you keep the array aligned so that they’re both looking at the same star/galaxy? What kind of resolution can you get from one dish and then also all of them? Thanks very much! — Paul
Answer: In fact, radio telescopes operate in two different ways. The simplest way for a radio telescope to make astronomical measurements is for it to operate in a stand-alone mode. In this mode the radio telescope collects signals from space just like a single optical telescope. At the focal point of the radio telescope one can place either a detector with a single pixel or one with multiple pixels, ...