This sounds like something Captain Kirk and the crew of the Starship Enterprise might investigate in an episode of "Star Trek": mysterious, ginormous clouds that are whirling around on the outskirts of the galaxy at incredible speeds.
Scientists have known about the existence of these high-velocity clouds — the clouds drift around in the galactic halo, outside the plane of the Milky Way — for quite some time, but until now, researchers didn't have the tools to truly map them out and study them. That's changed thanks to new research out of the International Center for Radio Astronomy Research (ICRAR), which has released the most detailed maps of the clouds to date.
The maps have been made public, so that anyone can download and study them.
Made using radio telescope data, the maps show clumps and branches within the clouds that have never been identified before. The research also shows the true scale and borders of these fast-moving puffs of gas, and their size is awe-inspiring. Some are millions of times the mass of the sun and over 80,000 light-years in diameter.
Maps offer new clues
"It's something that wasn't really visible in the past, and it could provide new clues about the origin of these clouds and the physical conditions within them," said Tobias Westmeier, an astronomer who was was involved with the creation of the maps, in a press release.
The reason these clouds are so mysterious is that they move independently of and distinguishable from the rotational movement of the galaxy itself, and their speed has been clocked at between 43.5 to 56 miles per second. No one knows why they're there or where they came from, but of course there are theories. Perhaps the most widespread notion is that the clouds are material that was leftover from the formation of the galaxy, but such a theory still requires an evaluation of why the clouds move as they do.
It's also possible that the clouds aren't from our galaxy at all, but strangers that have been caught in our gravitational embrace as the Milky Way scours through the cosmos. Right now, it's anybody's guess, which is why this new research is so important.
One clue is that the clouds have different compositions than what we typically find in the Milky Way, seeming to suggest that they share a different origin from us. Even so, they cover about 13 percent of the night sky, so they're not insignificant.
"These gas clouds are moving towards or away from us at speeds of up to a few hundred kilometers per second," said Westmeier. "They are clearly separate objects."
The research was published in the Monthly Notices of the Royal Astronomical Society.