Asteroid Apophis Bigger than Previously Thought, Says NASA

The European Space Agency's Herschel Space Observatory has captured images of the asteroid Apophis as it approached Earth this past weekend.

New observations show that the asteroid is larger than what was previously estimated. Apophis, named after an Egyptian demon, was first discovered in 2004. The asteroid was termed as the "doomsday asteroid", after initial reports suggested that there is a 2.7 percent chance of the asteroid impacting Earth in 2029. However, additional observations have ruled out the possibility of an impact.

According to NASA scientists, Apophis will approach close to Earth April 13, 2029, but will not cause any impact. It will pass at a distance of 18,000 miles above Earth's surface.

Apophis will approach Earth one more time in 2036. Astronomers are yet to ascertain how close it will pass Earth. But the asteroid approaching in 2029 is projected to change its orbit.

"In 2029, it will pass so close to us that Earth's gravity will change its orbit," professor Alan Fitzsimmons, an astronomer at Queen's University Belfast, UK, told BBC.

"Most of the potential orbits it will end up on will mean we are safe for the next 100 years. But there is a small region of space - something we call a keyhole - and if it passes through that keyhole in 2029, it will come back and hit us on 13 April in 2036."

The new data provided by Herschel Space Observatory shows that the asteroid is about 10,060 feet (325 meters) across, while earlier estimates suggested that the average diameter of the space rock is about 885 feet.

Scientists also analyzed heat emitted by Apophis and provided new estimates of the asteroid's reflectivity. The reflectivity of the space rock is calculated as 0.23, as against previous estimates of 0.33.

This means that 23 percent of the sunlight falling onto the asteroid will be reflected, while the rest is absorbed and heats up the asteroid.