Scientists working at the IceCube Neutrino Observatory in Antarctica have finally confirmed that the billions of subatomic particles whizzing through the ice at the tip of the planet actually originate from deep in outer space. According to a press release from the University of Wisconsin-Madison, the evidence confirms that the near-massless particles known as neutrinos are not of this solar system.

The high-energy particles are generated in what scientists called “nature’s accelerators” – black holes, exploding stars, and the centers of active galaxies. Researchers at the observatory in the South Pole detected 21 high-energy muons, which are created when neutrinos interact with other kinds of particles. The presence of these particles deep in the ice independently confirms the extragalactic origins of neutrinos.

The study’s findings were published in the journal Physical Review Letters on August 20. The IceCube Collaboration called the results an “unequivocal signal” for neutrinos from outer space, which likely traversed stars, galaxies, and solar systems at breakneck speeds, buzzing past most other forms of matter.

Neutrinos carry no charge and are virtually massless, which makes them difficult to detect. They are only observed when they crash into other particles, which results in the creation of a muon. There are multiple types of neutrinos, and the study was able to identify only the highest-energy particles that made it hear from distant galaxies.