This artist’s conception portrays a collection of planet-mass objects that have been flung out of the galactic center at speeds of 20 million miles per hour (10,000 km/s). These cosmic “spitballs” formed from fragments of a star that was shredded by the galaxy’s supermassive black hole. Image credit: Mark A. Garlick/CfA.

Cosmic ‘spitballs’ released from Milky Way’s black hole

You’ve never seen a rogue planet like this.

“Other galaxies like Andromeda are shooting these ‘spitballs’ at us all the time.” -James Guillochon, coauthor on the new study

Black holes don’t just provide gravity, absorb incoming matter and prevent anything from escaping. They also gravitationally pull on and tear matter that passes nearby, including stars. In a surprising find, a new study out of Harvard shows that torn-apart stars aren’t merely reduced into gas, but they form dense streams that re-condense into planets in just year-long timescales. Moving rapidly away from the central black hole, these ‘cosmic spitballs’ represent a brand new population of rogue planets, and are potentially the most catastrophic objects from space careening through our galaxy.

Rogue planets may not just form from nebulae, but from shredded stars encountering black holes. Image credit: Christine Pulliam / David Aguilar / CfA.

When a massive object — a star, gas cloud, planet, asteroid, etc. — gets too close to a black hole, it will find itself ‘spaghettified’. The tidal forces from the black hole will pull any matter closer to its center more strongly than the matter that’s more distant, causing it to get stretched and compressed into a long, thin, spaghetti-like…