The Milky Way is blowing bubbles. Two giant radio bubbles, extending out from the galaxy for over 1,400 light years, were just discovered in new data. Astronomers think the bubbles started forming a few million years ago due to some type of cataclysmic event near the galaxy’s central supermassive black hole.

The bubbles’ location also closely matches the range of over 100 narrow, magnetized filaments of radio emissions that stretch for tens of light-years in length. First discovered 35 years ago, these filaments’ origins have remained a mystery, but the bubbles’ discovery may now provide an answer.

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“The filaments have been a mystery for a long time,” said Ian Heywood, astronomer at the University of Oxford and lead author on the new discovery. He says their results hint that the event that created the bubbles could have also produced high-energy charged particles that created the filaments.

The symmetry of the bubbles billowing above and below the galaxy suggests they were formed by an extremely energetic explosion near the supermassive black hole at the center of the Milky Way. The most likely explanation is a flare up in the black hole’s activity as it gobbled up extra nearby material and burped out other particles and radiation. The bubbles could also have been created by an extreme burst in star formation that sent a shock wave across the galactic center. Or possibly, it was a combination of both events.

The discovery, published on September 11 in the journal Nature, used the MeerKAT telescope, a radio telescope with 64 antennas, at the South African Radio Astronomy Observatory (SARAO) in South Africa. Astronomers there were taking some of the first science images with the new telescope, looking at the radio emissions of the central galactic region, when they made the surprising discovery.