The Intergalactic Winds That Built the Milky Way
Even though there’s no air blowing around in space, the cosmos can be a pretty windy place. Winds made of gas particles whip around galaxies at high speeds, measuring hundreds of kilometers per second. Astronomers suspect they’re created by supernovae, when nearby stars explode and send streams of photons powerful enough to push around gas. This wind can be ejected out of galaxies into intergalactic space. Some of the wind will keep traveling into the void, while a fraction will get sucked back in—a process known as wind recycling.
