Sometimes, the powerful radio bursts detected by our telescopes have the look of alien beacons. Other times, they're caused by scientists reheating coffee.
The latter happens to be the case when it comes to the origin of mysterious radio signals known as perytons. For years, astronomers at the Parkes Observatory in Australia have puzzled over these brief but intense bursts, which in some ways appeared to emanate from deep space. But unlike the fast radio bursts we've also heard about recently, researchers knew that perytons were actually coming from somewhere nearby, because they would simultaneously show up in multiple viewing fields rather than emanating from a single source.
But no one suspected perytons were coming from the lunch room, until astronomer Emily Petroff decided to install a real-time radio interference monitor at the Parkes telescope. National Geographic's Nadia Drake describes what happened next:
In January, the telescope detected three of the [peryton] signals -- and the interference monitor picked up three simultaneous interference signatures. The team recognised the interloping frequencies as possibly belonging to a microwave oven.
When Petroff and her colleagues tested their hypothesis, they found they could create perytons on demand simply by opening the oven door before the timer had dinged.
There you have it. One astronomical mystery, at least, has a simple answer: people are impatient to get at their Hot Pockets. Apparently, when you open a microwave oven's door before the timer goes off, the magnetron inside doesn't have time to shut off completely, so you end up releasing a burst of radio waves into the room.
It remains to be seen whether fast radio bursts will also end up having an Earthly origin. But with the way things have been going, I'll admit my faith that aliens are trying to snapchat us from deep space is flagging a bit.
Now, aliens living inside my microwave oven, that's another story.
Read a pre-print of the scientific paper at arXiv.