NASA: Asteroid to pass by Earth on Christmas Eve

NASA scientists calculate that asteroid 163899, also known as 2003 SD220, will make its closest approach to Earth on Christmas Eve, December 24, 2015.

The asteroid is rather large, thought to measure between 0.5 and 1.5 miles wide. Contrary to reports that it will graze Earth or trigger earthquakes, the asteroid won’t actually come all that close.

The space rock will remain at a safe distance of 6,787,600 miles, more than 28 times the distance between Earth and the Moon. By comparison, the asteroid on Halloween flashed by at just 1.3 times the Earth-Moon distance, and even that flyby wasn’t a cause for concern.

“Again, there is no existing evidence that an asteroid or any other celestial object is on a trajectory that will impact Earth,” Paul Chodas, manager of NASA’s Near-Earth Object office at the Jet Propulsion Laboratory, said in a statement released this summer. “In fact, not a single one of the known objects has any credible chance of hitting our planet over the next century.”

The coming asteroid flyby will offer astronomers a decent chance at securing focused radar images of the rock in the days leading up to Christmas. Backyard astronomers may even be able to spot the asteroid with a telescope and a little planning.

If the asteroid whizzes by without being seen, there will be another chance at a glimpse in just a few years.

“The 2015 apparition is the first of five encounters by this object in the next 12 years when it will be close enough for a radar detection,” NASA asteroid researchers wrote in a blog update.

“By obtaining radar ranging measurements at each observing opportunity, it may be possible to detect non-gravitational perturbations due to the Yarkovsky effect,” the post continued. “If so, then we can obtain an estimate of the object’s mass, information that is invaluable for understanding the object’s bulk density and internal structure.”

The Yarkovsky effect is the rotational force enacted on the asteroid as it is heated and cooled by solar radiation. The effect can slightly alter an asteroid’s orbital path over time, and better understanding it is key to more accurately predicting the trajectories of future asteroids.

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