Wednesday, November 11, 2015

Apophis to Be Visible to the Naked Eye, Other Large Hazardous Asteroids Still Unknown, Says ESA Official

The potentially dangerous asteroid Apophis (circled) is seen here, in a composite of five exposures taken Jan. 31, 2011, by a telescope in Hawaii. Credit: D. Tholen, M. Micheli, G. Elliott, UH Institute for Astronomy

It’s really not very often when a large asteroid, capable of capable of killing millions, is passing very close our home planet. On Oct. 31 this year, the 600 meters-wide asteroid 2015 TB145 gave us a close shave, missing the Earth at a distance of 490,000 kilometers. It was the first flyby of an asteroid that large since November 2011, when the asteroid 2005 YU55 - 300 meters in diameter - passed at about 0.85 lunar distances (324,900 kilometers). However, more worrying encounters may be yet to come, like the famed Apophis or killer space rocks that haven’t been spotted yet.

Apophis is a near-Earth asteroid that caused a real stir when it was reported that it would hit Earth on Apr. 13, 2029. Now when we know that this 375 meters-wide rock poses no danger to us, it is still an important object for scientists to keep an eye on for assessing the risk of potential future impacts. Thanks to the fact that Apophis will come relatively very close, it will be a great target for observations, even for the naked eye.

“The 375 meters-wide Apophis will approach Earth in April 2029 to less than 30,000 kilometers and become visible with the naked eye,” Gerhard Drolshagen, European Space Agency’s (ESA) Space Situational Awareness (SSA) Programme Manager, told astrowatch.net.

SSA detects, predicts and assesses the risk to life and property due to man-made space debris objects, reentries, in-orbit explosions and release events, in-orbit collisions, disruption of missions and satellite-based service capabilities, potential impacts of Near-Earth Objects (NEOs), and the effects of space weather phenomena on space- and ground-based infrastructure.

The NEO segment of SSA is continuously scanning the sky for NEOs, predicting their orbital evolution and impact risk, storing observational and calculated data, issuing NEO information, news releases and impact warnings and supporting NEO mitigation measures in close coordination with international partners.

“Already now ESA predicts the orbits of all newly discovered near-Earth asteroids and predicts the impact risk for the coming 100 years,” Drolshagen said.

He pointed out that we should be aware of many yet undiscovered potential hazardous asteroids lurking somewhere in space.

“Other large asteroids that could come close might still be unknown,” Drolshagen noted.

Having in mind that the asteroid 2015 TB145 was spotted only three weeks ahead of its flyby, it could be a reminder of many potential dangers yet undiscovered. As of Nov. 11, 2015, there were 1633 known potentially hazardous asteroids (PHAs). None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time. On Nov. 29, 2015, an enormous asteroid, designated 2003 EB50 will flyby Earth. But luckily, the 2.2 kilometer-wide space rock will pass at very safe distance of about 48 lunar distances.

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