Scientists have spotted a mammoth gas cloud that is boomeranging back to its birthplace: the Milky Way galaxy. The Smith Cloud is plummeting towards our galaxy at a speed of 1.13 million kilometers per hour. Andrew Fox of the Space Telescope Science Institute in Baltimore said in a statement the gas cloud is 11,000 light years long and 2,500 light years across.
It will plow into Milky Way in 30 million years
Findings of the study were published in the Astrophysical Journal Letters. Hundreds of high-velocity gas clouds on the outskirts of the galaxy are known to astronomers. But Smith Cloud is unique because its trajectory is well known. Researchers have been monitoring it since the 1960s when doctoral astronomy student Gail Smith first detected radio waves emitted by its hydrogen.
Scientists who studied the Smith Cloud using NASA’s Hubble Space Telescope said it would plow into Milky Way within 30 million years. The study shows that the gas cloud was ejected from the outer regions of the galactic disk about 70 million years ago. But the ejection was not strong enough to break it completely free of the galaxy’s gravity. Now it is on a return collision course.
Smith Cloud could lead to formation of 2 million stars
When it collides into the Milky Way, the Smith Cloud will ignite a huge burst of star formation. Researchers believe that it will provide enough gas to form 2 million suns. Previously, astronomers believed that the cloud belonged to the interstellar space or a starless galaxy. Fresh evidence suggests that the Smith Cloud was actually born in the Milky Way galaxy. The cloud is orbiting our galaxy at a very high speed. Every year, it gets pulled closer to the Milky Way.
Scientists used the Hubble Space Telescope to measure its chemical composition. They found that it was rich in sulfur just like the outer disk of Milky Way. This means the cloud was enriched by material from stars. If it was from the interstellar space or a starless galaxy, it would be rich in pristine hydrogen and helium. The Smith Cloud is an example of how our galaxy is changing with time.