Hubble Space Telescope astronomers are tracking an invisible hydrogen gas cloud that is aimed back toward earth at nearly 700,000 miles per-hour. Though there are hundreds of gas clouds in our galaxy, the “Smith Cloud” is unique because astronomers know its trajectory ... Earth. Do we need to evacuate?
Named after doctoral astronomy student Gail Smith, who detected radio waves emitted by the cloud in the 1960’s, Hubble scientists have observed that the cloud was most likely ejected from our Milky Way Galaxy 70 million years ago.
Team Leader Andrew Fox of the Space Telescope Science Institute in Baltimore explained in a press release,
The cloud is an example of how the galaxy is changing over time. 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 to another.
The gas cloud is comet-shaped and estimated to be 11,000 light-years long and 2,500 light-years across. It is 30 times bigger than a full moon. Its chemical composition was determined using Hubble’s Cosmic Origins Spectrograph to measure how much light filtered through the cloud.
It was determined that the cloud is rich in sulfur, as is the Milky Way’s outer disk, a region about 40,000 light-years from the galaxy’s center and about 15,000 light-years farther out than our sun and solar system. Thus, the cloud was most likely launched from within the Milky Way. It’s coming home!
When the giant gas cloud returns to our solar system, it may result in a massive burst of star formation, creating as many as two million suns.
No need to worry. The collision is expected to occur in 30 million years.