The signal came from… inside the observatory!

A peryton is a brief but intense burst of radio waves that have been baffling astronomers for some time. Since the 1990s, astronomers at radio telescopes have been detecting them and wondering if they came from deep space, and what they could mean. Recently the found out: lunch is ready!

Perytons produced on our planet

Researchers from the Parkes Observatory in Australia unraveled the mystery earlier this month. One of the big issues with perytons being from deep space is that they were generally detected in multiple viewing fields, rather than coming from a single point far away. The odds that more than one matching signal would be arriving at a radio telescope simultaneously from multiple points of origin would just be… astronomical! (sorry!) But guessing that the perytons were originating closer to Earth still didn’t explain what they were.

Finally, with additional surveillance by a real-time radio interference monitor, three signals were detected. The frequencies of those signals were recognized as matching a microwave oven, which then explained a pattern nobody had picked up on yet; perytons were most often detected at lunch time.

Signal source hiding in plain sight

So how did we get go this long without putting two and two together? This is partly due to the fact that just operating a microwave isn’t enough to release the radio signal, as they are shielded devices. Some observatories also ban microwave ovens (and phones, wifi-routers, etc.) outright or have them in Faraday cages. So there wasn’t a consistent, obvious, 1:1 pattern to pick up on.

The perytons were only detected when the door of the running microwave was opened before the timer finished. Only in that small instant between the door unlatching and the magnetron shutting off the oven were sufficient radio waves released. And since that’s not necessarily the most common event with the microwave oven, the link was harder to make.

Once the link was made, however, the researchers were able to consistently reproduce the event on command, basically solving the mystery. But perytons weren’t the only mysterious signals detected at these observatories. A different signal, called fast radio bursts, still has an unexplained origin— one most people are sure are coming from deep space. Hopefully. It’s hard to say until they confirm that the refrigerator has been cleaned out.

Source: Rogue Microwave Ovens Are the Culprits Behind Mysterious Radio Signals by Nadia Drake, No Place Like Home