Julia Sklar, reporter
It's not often that we have two space rocks simultaneously vying for attention down here on Earth. A meteor blast in Russia has hogged the headlines today, but eyes are now turning to asteroid 2012 DA14, which will soar past us shortly in the closest fly-by for an asteroid this size in recorded history (see its trajectory in the video above). Some are hoping that the rock's unmatched combination of size and proximity could allow us to see an asteroid quake in action for the first time.
Most asteroids are dark red, a result of "space weathering" - prolonged exposure to cosmic rays and solar radiation. But a few are light-coloured. Research by Richard Binzel of the Massachusetts Institute of Technology reckons that this is because these asteroids have had a close encounter with Earth some time in the past million years. The gravitational pull from Earth could rock the asteroid, he suggests, causing a quake and effectively shaking off its space weathering.
"Gravitational forces during the fly-bys can stretch, rattle and torque these asteroids, causing dark, space-weathered material on the surface to be overturned, revealing the fresh stuff underneath," Binzel said in an interview with NASA.
Today, Binzel and his team are carefully observing the asteroid's approach. Given its size - roughly 45 metres wide - and nearness - it is expected to pass just 27,700 kilometres from Earth - they will be able to measure changes in colour, spin, shape and reflectivity, which would be clues to the occurrence of such a quake.
Measurements will be made through telescopes all over the world, including La Palma in the Canary Islands, the Siding Spring, Perth and Mount Canopus observatories in Australia, Mount John in New Zealand, Wise in Israel and the Clay Center in Massachusetts.
chauncey billups caucus results exton kurt warner kurt warner ricky williams missouri primary
কোন মন্তব্য নেই:
একটি মন্তব্য পোস্ট করুন