There is always a reason to look up, literally and figuratively—astronomers tend to be an optimistic group, and the past few months have been especially fruitful in terms of naked-eye celestial sitings. If you ventured outside at all, you probably could not help but notice Venus in the evening sky, or as it transitioned to a ‘morning star’ at the beginning of June. There were meteor showers in April and May, and, of course, the detection of Comet NEOWISE.
Comets like NEOWISE generate excitement because ordinary people can see their visible emission with their own eyes from their backyards (or the nearest low-light pollution vantage point). Astronomers, however, can obtain greater insights from a multi-wavelength perspective and radio observations of comets are no exception.
Radio telescopes had been trying to observe comets since the 1950s with little success. The signal from a comet is so weak that large radio telescopes, equipped with sensitive receivers, were needed. It wasn’t until the 1970s that the first successful detection of a comet at radio wavelengths was observed, by a giant radio antenna—the Nancay Telescope—in France.
In Nancay, France looms this enormous radio telescope. This portion represents a section of a sphere that reflects ...