Milky Way faster than thought

[hamid]

O ur planet -- along with the whole solar system -- is rushing through space 160,000 km/h faster than we thought, says a new analysis of Earth's place in the universe.


Oh, and the risk of crashing into something really big--like another galaxy -- is apparently much higher than what was previously thought, too.
The findings are part of a new look at our galaxy, the Milky Way, which is actually harder to see than far-off galaxies because we're inside it. In some regions, the glare is blinding to telescopes.
Earth's revised speed: 965,000 km/hinanorbit around the Milky Way's centre.


And since we and our neighbouring stars are moving faster than previously thought, yet we're not being flung off into space, astronomers have recalculated the mass that holds all that speeding stuff together. Result: the Milky Way must be 50 per cent heavier than they had previously figured. This means our galaxy has more gravity, and is therefore pulling harder on neighbouring galaxies such as Andromeda. That raises the chance that some day, they will crash together, though not for a few billion years.
The findings come from German and American astronomers using the U. S. National Science Foundation's Very Long Baseline Array radio telescope to rewrite the map of the Milky Way. The array is a network of 10 radio-telescope antennas stretching from Hawaii to New England and the Caribbean.
They reported their results Monday at the American Astronomical Society's meeting in California.
Even the shape of the Milky Way is a surprise, says Mark Reid of the Harvard-Smithsonian Center for Astrophysics.The old theory was the galaxy is a spinning disk, with two arms spiralling out from the centre.
"These (new) measurements indicate that our galaxy probably has four, not two, spiral arms of gas and dust that are forming stars," he said.
This illustrates a problem of astronomy: that some of the biggest mysteries lie close to home.
"Because we're inside it, it's difficult for us to determine the Milky Way's structure," he said. "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. We have to deduce its structure by measuring and mapping."
Earth is in one of the spiral arms, so far from the galaxy's centre that it takes 28,000 light years to travel that distance. The whole galaxy has at least 200 billion stars, and possibly 400 billion.