Not-so-killer asteroid: Astronomers rule out Earth impact of Apophis

Since its discovery in 2004, asteroid Apophis, a near-Earth object (NEO) - has captivated both scientists and the public with its potential close encounters with Earth in 2029 and 2036. While scientists have long ruled out the risk of impact during these encounters, a new study led by Western astronomer Paul Wiegert and collaborator Benjamin Hyatt from the University of Waterloo meticulously calculated the paths of all 1.3 million known asteroids in the Solar System to rule out the possibility that Apophis could strike another asteroid, redirecting its predicted path towards Earth.

"We calculated the paths of all known asteroids using a detailed computer simulation of our Solar System and the possibility of such an unlikely event was evaluated. Fortunately, no such collisions are anticipated," said Wiegert, a physics & astronomy professor.

Also known as asteroid 99942, asteroid Apophis was discovered on June 19, 2004, and is estimated to be about 335 metres across. It is a remnant from the early formation of our solar system about 4.6 billion years ago.

Wiegert and Hyatt identified the closest passages between known asteroids and Apophis for future monitoring to maintain situational awareness and to refine their orbits, but the overall risk of the asteroid colliding with a known asteroid in future is all but zero.

"Asteroid Apophis has fascinated us as a species since its discovery in 2004: it was the first credible threat from an asteroid to our planet. Even now that we know it's on course to miss us by a safe margin, astronomers remain vigilant. It's the asteroid we just can't stop watching," said Wiegert, a member of the Institute for Earth and Space Exploration.