Parkes radio telescope
WHAT’S FOR DINNER? Signals detected by the Parkes radio telescope (pictured) suggest that intelligent life in the universe has a penchant for leftovers.

Excerpt from sciencenews.org

Mysterious radio signals detected by the Parkes telescope appear to come from an advanced civilization in the Milky Way. 

Unfortunately, it’s the one civilization we already know about.
Microwave ovens opened before they’re done cooking have been muddling the hunt for far more distant radio signals, researchers report online April 9 at arXiv.org. Astronomers have had to contend with enigmatic flares dubbed “perytons” ever since discovering equally puzzling fast radio bursts, or FRBs (SN: 8/9/14, p. 22), in 2007. Perytons and FRBs are quite similar, except that astronomers realized that perytons originate on Earth, possibly from some meteorological phenomenon, while FRBs come from other galaxies.

Three perytons in January coincided with independently detected blasts of 2.4 gigahertz radio waves — the same frequency that microwave ovens use to heat food. So researchers at the Parkes telescope in Australia spent weeks heating mugs of water while moving the massive radio dish around the sky, trying to re-create the phenomenon. Finally, researchers tried opening the oven door mid-cooking instead of letting the timer run out. Suddenly, perytons started showing up in the data.

The source of the galactic FRBs remain an intriguing mystery. Astronomers suspect they have something to do with imploding neutron stars or eruptions on magnetars. At this point, however, they might want to consider extraterrestrials nuking frozen pizzas.