"AN asteroid four times the length of a football field will pass closer to Earth than the moon when it hurtles through our solar system tomorrow morning. The asteroid is the first object of its size to come so close to the Earth, flying within 320,000 kilometres of our planet, in more than 30 years. But its trajectory has been well studied since it was discovered in 2005 and there was no threat of an Earth collision for at least the next 100 years, NASA says. Advertisement: Story continues below Nor was there any risk the rock, known as 2005 YU55, would make contact with the moon or any other celestial body when it zooms past at close to 19 kilometres a second relative to the Earth's speed. An astrophysicist at the Australian National University, Paul Francis, said if a space rock the size, shape and speed of 2005 YU55 did collide with our planet it would ''certainly take out a medium-sized continent,'' or, if it landed in the ocean, create a 500-metre high tsunami. ''If it landed in Sydney, you'd probably be dead in Canberra,'' Professor Francis said. The asteroid's closest encounter will be about 10.30am Australian time, but it will not be visible from most regions of the southern hemisphere because it will be daylight. Amateur astronomers in Europe and North America will be able to catch a glimpse with a small telescope and a clear sky. Professor Francis said the path of about 90 per cent of large asteroids, those that measure many kilometres in diameter, had been tracked. ''And none are currently on a collision course with Earth,'' he said. Glen Nagle, from CSIRO's NASA tracking station at Tidbinbilla, said NASA had been tracking the asteroid with its radio telescopes since Friday. ''The radio mapping will … give us more information about its density, its speed and composition,'' he said. Read more: http://www.smh.com.au/technology/sci-tech/asteroid-on-track-for-close-encounter-20111107-1n3ve.html#ixzz1d4oIMEKA" Article from SMH All the methods of deflecting an object such as this seem to be science fiction at the moment. And even it they could be done who would be willing to but up the money to prevent a collision that might never happen? Or is it just a matter of time?