Added 1 new A* page:NASA just posted an article about the Smith Cloud, a cloud of hydrogen just outside the outer edge of our galaxy, but so large—11,000 light years long and 2,500 light years across—that, if it were visible to the eye (the hydrogen is invisible in visible light—it was discovered "in the early 1960s by doctoral astronomy student Gail Smith, who detected the radio waves emitted by its hydrogen"), it would appear 30 times as wide as the full moon in our sky.
NASA says that "hundreds of enormous, high-velocity gas clouds whiz around the outskirts of our galaxy," but for Smith, they've actually been able to calculate its trajectory: currently moving at 700,000 miles per hour, it came out of our galaxy 70 million years ago, and will run back into it in 30 million years, at which point "astronomers believe it will ignite a spectacular burst of star formation, perhaps providing enough gas to make 2 million suns."
For a long time, it was suggested that Smith was a failed dwarf galaxy that had collided with the Milky Way, but new spectrographic measurements taken by Hubble indicate "the Smith Cloud is as rich in sulfur as the Milky Way’s outer disk," which pretty much nixes the failed galaxy theory, and instead suggests that the cloud was a part of our own galaxy that was vigorously ejected—what caused that is still unknown!
|
