Asteroid flyby cause no danger to Earth

“A piece of space rock what we commonly call an asteroid with size slightly bigger than a play ground will closely pass the earth on the early hours of Wednesday, November 9, 2011 with its closest approach to the earth at 4.58 am Sri Lankan time.

“According to the calculations made by astronomers, it will not hit the earth and therefore cause no danger to our planet.

This asteroid, named as 2005 YU55, was an asteroid discovered on December 28, 2005 and it has a spherical shape, diameter 400 metres, jet black in colour due to its carbon rich composition, and weighs 55 million tonnes.

It orbits around the Sun once in every 1.22 years while rotating around its own axis like a planet once in every 18 hours. During the current flyby its closest distance from the earth will be around 325,000 km, which is lesser than the average earth-moon distance of 384,000 km (i.e about 85 percent the distance from Earth to the Moon),” says Dr Chandana Jayaratne, Senior Lecturer in Physics, University of Colombo and Consultant to the Space Science Division Arthur C Clarke Institute for Modern Technologies.

“Asteroids this nature have passed by Earth at similar distances many times before, but this is the first time astronomers have known about a close flyby in advance.

For instance, a similar encounter occurred in 1976 with another asteroid was found by researchers 24 years later.

Therefore, this gives a rare opportunity for asteroid research. Understanding its chemical composition would help us to enhance our understanding about the basic building blocks of the solar system.

“Though it goes close to the earth due to its jet black appearance, naked eye observers cannot see it. You ought to have a decent telescope, preferably an eight-inch (20 cm) or bigger telescope to catch this 11.2 magnitude object,” said Dr Jayaratne.

“Orbit calculations made by astronomers reveals that, although classified as a potentially hazardous object, 2005 YU55 poses no threat of an earth collision over at least the next 100 years. Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100 metres that can come closer to Earth than 7.5 million kilometres.

By November 7, 2011 there were such 1,256 potentially hazardous asteroids discovered by the astronomers.

If 2005 YU55 were to collide with the Earth, it would blast out a crater six kilometres across and 500 metres deep, giving rise to a magnitude-7 earthquake and 20 metre-high tsunami waves!.”

The next time a known asteroid this nature will travel close to the Earth in 2028 when 2001 WN5 passes at a distance of 248,000 km from the Earth,” Dr Jayaratne said.