Giant Gas Cloud On Crash Course With Milky Way, Could Create 2 Million New Stars Upon Collision

A giant 11,000 light-year long gas cloud that was hurled from the Milky Way 70 million years ago has changed course and is headed straight back to our galaxy on a collision course of galactic proportions. The gigantic Smith Cloud is set to collide with the Milky Way as it travels 700,000 MPH in a collision that will likely create two million new stars.

The Daily Mail reports that the enormous Smith Cloud will collide with the Milky Way. The intergalactic fog will cause the galaxy to light up as two million more stars are born when the Smith Cloud and Milky Way collide in spectacular fashion. Sadly for those hoping to witness the skies light up with new stars, the collision isn’t set to take place for another 30 million years.

Trajectory of Smith Cloud
NASA showcases the projected trajectory of the Smith Cloud. (Image via NASA/ESA/A. Feild (STScI))

Scientists have long been watching the Smith Cloud as it appeared to be heading towards our galaxy for some time. However, researchers just recently discovered that the Smith Cloud was actually ejected out of the Milky Way 70 million years ago. Though it was hurled away from the Milky Way those millions of years ago, it is now headed back to its place of birth in boomerang fashion.

In fact, the Smith Cloud was discovered back in the 1960s when scientists initially believed it to be a failed galaxy. Other scientists during that time conjectured that the gas cloud was an intergalactic gas cloud simply moving between galaxies. However, they discovered the composition of the Smith Cloud contained heavy elements found within our own sun. Following the new discovery of star-produced elements instead of lighter elements such as hydrogen and helium, the scientists realized that the Smith Cloud was not a rogue gas cloud but rather a cloud of gas that at one point was ejected from the Milky Way.

Dr Andrew Fox, from the Space Telescope Science Institute in Baltimore, Maryland, notes that the Smith Cloud is a great example of how the galaxy changes over time, with gases being expelled from the galaxy only to return millions of years later when they boomerang back towards the Milky Way.

“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.”

Fox notes that though the crash won’t take place in any of our lifetimes, the Hubble telescope measurements and observations are helping paint a picture of what the collision will be like 30 million years from now. Dr Nicolas Lehner, an astrophysicist at University of Notre Dame, notes that with star-forming elements present, when the gas cloud collides with the Milky Way, it will likely cause two million new stars to be born. However, the Smith Cloud isn’t the only gas cloud slated to renew the stars of the Milky Way.

Smith Cloud and the Milky Way
NASA shows the velocity of the Smith Cloud as it approaches the Milky Way. (Image via NASA/ESA/A. Feild (STScI))

Lehner notes that there have been numerous large-scale gas clouds found in the halo of the Milky Way. All these gas clouds could later be ejected and boomeranged back towards the Milky Way in a cycle that would continue to allow the Milky Way to brighten with new stars.

“We have found several massive gas clouds in the Milky Way halo that may serve as future fuel for star formation in its disk, but, for most of them, their origins remain a mystery. The Smith Cloud is certainly one of the best examples that shows that recycled gas is an important mechanism in the evolution of galaxies.”

[Image via NASA/Saxton/Lockman/NRAO/AUI/NSF/Mellinger]