May 3, 2010

Earth Saved: Arecibo Sees Asteroid Fly By

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After the YU55 asteroid was discovered in 2005, astronomers feared that the asteroid might impact the earth. But after two days of observation at Cornell’s Arecibo Observatory in Puerto Rico last month, scientists were able to conclusively predict the distance at which the asteroid would pass.

The scientists at the observatory estimate that the asteroid, which passed Earth on Apr. 19, traveled within 1.5 million miles of the planet, or six times the distance between Earth and the moon. The scientists also predicted the asteroid was a quarter mile long and twice as large as had been previously estimated, according to the University.Though the NASA Near-Earth Object Program looks at a variety of asteroids as they orbit the earth, the predictions are not always so decisive, said Michael Nolan, a planetary scientist at the observatory. “This was a very clear case,” he said. “It was a big deal that in this case, we were able to make such a clear determination.” The next time that the asteroid will pass the earth will be Nov. 2011. At that time, the asteroid is expected to pass even closer: 0.8 times the distance between the earth and the moon. However, the scientists do not expect the asteroid to hit Earth anytime soon. “We know it won’t hit in the next hundred years,” Nolan said. However, Nolan said that the observatory’s ability to predict how closely the asteroid will pass to Earth is hampered by the fact that Earth’s gravitational field affects the asteroid’s orbit as it passes. “[YU55] will swing by the earth, and that will perturb the orbit. We don’t know exactly where it will go again,” Nolan said. “Eventually it might hit the Earth, but we can’t predict that far ahead.” Nolan said the accuracy of Arecibo’s predictions demonstrates the value that the telescope provides to the scientific community as the telescope goes up for funding reassessments by the National Science Foundation this year.Arecibo Observatory opened in 1963, and is one of the world’s largest and most powerful. The telescope is funded by the National Science Foundation, and operated by Cornell University.

Correction: An earlier version of this story incorrectly stated the year in which the Arecibo Observatory opened. It was 1963.

Original Author: Juan Forrer