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There's a Giant Cloud on a Collision Course With the Milky Way

At 11,000 light years long and 2,500 light years wide, Smith’s Cloud is not your average ball of vapor.

by Becky Ferreira
Oct 9 2016, 9:00pm

Smith's Cloud's trajectory. Image: NASA/ESA/A. Feild (STScI)

Mark your epochal calendars, because 30 million years from now, a massive billow of gas called Smith's Cloud is due to crash into the Milky Way, according to a video released on Friday by NASA.

First discovered in 1963 by radio astronomer Gail Smith, the cloud measures an astonishing 11,000 light years in length by 2,500 light years in width, and it is traveling towards our galaxy at the breakneck pace of 700,000 miles per hour.

Scientists think that this spectral formation, made mostly from hydrogen gas, was kicked out of the Milky Way about 70 million years ago, when dinosaurs still roamed Earth. This conclusion is based on precision observations by instruments like the Hubble Space Telescope, which revealed that the cloud appears to be enriched with traces of heavier elements like sulfur gas at around the same concentrations as the outer galactic disk.

Smith's Cloud's trajectory. Image: NASA/ESA/A. Feild (STScI)

The sulfur match suggests that Smith's Cloud hails from the Milky Way, and does not, as previous research proposed, originate outside of the galaxy. However, nobody knows what mechanism initially punted the cloud out into galactic orbit all those millions of years ago.

Regardless, the exile has boomeranged back and is on track to collide with the outer Perseus arm of the Milky Way, an event that will spark spectacular stellar fireworks. Indeed, Smith's Cloud may contain enough raw dough to bake up two million new Sunlike stars as it is absorbed into its galactic host, according to NASA.

READ MORE: What Is This X-Shape at the Center of the Milky Way?

This burst of energetic star formation will occur thousands of light years from Earth, so it is not likely to pose any dangers to whomever happens to be occupying our planet 30 million years from now (cylons, probably). But it will make for a stunning light show, as well as a reminder that the Milky Way is constantly evolving on a cosmic scale.

"The cloud is an example of how the galaxy is changing with time," Andrew Fox, an astronomer based at the Space Telescope Science Institute and a leading Smith's Cloud researcher, said in a NASA statement. "It's telling us that the Milky Way is a bubbling, very active place where gas can be thrown out of one part of the disk and then return back down into another."

"Our galaxy is recycling its gas through clouds, the Smith Cloud being one example, and will form stars in different places than before," he added. "Hubble's measurements of the Smith Cloud are helping us to visualize how active the disks of galaxies are."

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