Radio telescopes detect signals at a longer wavelength than optical telescopes, making them ideal for looking at gases but not light or stars. In 1970, a pair of astronomers named Wade and Hjellming decided to use their three precious weeks of observing time on a radio telescope to see if a certain type of star called a red supergiant was detectable. After two weeks of searching, the answer was a disappointing “no.” They moved onto the backup plan: using their last week to point the telescope at various other types of stars in the hopes they could find something.
And they did! They detected a strong signal when they pointed the telescope at a nova, or exploding star, and then shortly after, a second one. Building on those successes they completely changed their observing strategy to focus on all types of novae, ultimately leading to the discovery of a new class of radio source and providing a valuable complement to the existing optical data on novae.
There was one small catch — they had mis-typed a digit when filling out the punch card that feeds coordinates to the telescope, and the first thing they had detected was actually radio waves from a known radio source, not a nova. Same thing for the second detection: a calculation error meant that they had been pointing at the wrong patch of sky. The fact that they kept looking specifically at novae with the radio telescope was propelled by a few silly mistakes that just happened to lead them down the right path of inquiry. As Wade wrote: “When you can’t do [science] any other way, that’s how you have to do it!”