Risk of collision with another galaxy
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A team of international astronomers have determined that the Milky Way, the Earth's home galaxy, is spinning much faster and has a mass 50 percent larger than believed, raising the probability of a collision with another galaxy.
AFP - The Milky Way, the Earth's home galaxy, is spinning much faster and has a mass 50 percent larger than previously believed, raising the probability of a collision with another galaxy, according to a report out Monday.
A team of international astronomers, with the aid of ten telescopes spread out between Hawaii, the Caribbean and the northeastern United States, determined that the Milky Way is rotating at a speed of 161,000 kilometers (100,000 miles) per hour faster than previously thought.
That increase in speed increases the Milky Way's mass by 50 percent, said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics, in research presented at the American Astronomical Society meeting this week in Long Beach, California.
"No longer will we think of the Milky Way as the little sister of the Andromeda Galaxy," Reid said in a statement.
The larger mass however also means that it has a greater gravitational pull, which increases the likelihood of collisions with the Andromeda galaxy or smaller nearby galaxies, Reid said.
The earth's solar system is located some 28,000 light years from the center of the Milky Way.
At that distance, the new measurements show that the galaxy is rotating at a speed of 965,600 kilometers (600,000 miles) per hour, compared to previous estimates of 804,672 kilometers (500,000 miles) per hour, the astronomers said.
The new observations from the network of radio telescopes is "producing highly-accurate direct measurements of distances and motions," said Karl Menten of the Max Planck Institute for Radio Astronomy in Germany, a member of the team.
"These measurements use the traditional surveyor's method of triangulation and do not depend on any assumptions based on other properties, such as brightness," Menten said.
The direct measurements "are revising our understanding of the structure and motions of our Galaxy," Menten said.
It is difficult to determine the structure of the Milky Way because the Earth is inside it. "For other galaxies, we can simply look at them and see their structure, but we can't do this to get an overall image of the Milky Way," Menten said.
"We have to deduce its structure by measuring and mapping," he added.
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