A giant detector buried deep within the Antarctic ice at the South Pole has obtained the first evidence of eerie particles called neutrinos coming from the innards of our own home galaxy, the Milky Way.
The discovery is a step towards scientists being better able to use particles to study hidden or elusive phenomena in the universe, rather than having to rely on light seen by telescopes.
Neutrinos are subatomic particles that have been compared to "ghosts slipping through the night," because they're so insubstantial and seem to barely interact with the rest of the physical world.
The Earth is constantly being bombarded by neutrinos, but most originate in the sun or in the atmosphere.
A decade ago, a particle detector known as the IceCube Neutrino Observatory managed to find neutrinos coming from outside our solar system.
They've known that some are coming from outside our galaxy, and they figured that some must come from the Milky Way, too. IceCube has been hunting for those.
"It was accepted that there would be neutrinos coming from our galaxy, but we didn't have any evidence until now," says Ignacio Taboada, a professor of physics at the Georgia Institute of Technology and IceCube's spokesperson.
The IceCube team says in the journal Science that it's used machine-learning techniques to sort through ten years of data, revealing neutrinos emanating from the inner parts of the Milky Way.
But it's not yet clear whether the neutrinos are coming from a collection of specific sources or if it's a more diffuse kind of emission. "It's probably a combination of both," Taboada says.
One of the most exciting things about this discovery is the possibilities it opens up for learning more about the origins of cosmic rays, he says.
Cosmic rays are subatomic particles that travel through the universe at almost the speed of light, and although they have been studied for over a century, much about them remains mysterious.
