The massive asteroid 99942 Apophis was formerly believed to be one of the deadliest asteroids in space with a high chance of colliding with Earth. The 370-meter asteroid’s approach towards Earth caused widespread concern when it was first identified, raising fears of an actual collision.
However, new data acquired by astronomers makes this circumstance now appear unlikely. As a result, NASA has declared Earth to be asteroid-free for the next century.
Nevertheless, the asteroid Apophis remains a cause for concern and that’s because of the proximity of its flyby to us in 2029.
How close will Apophis come?
Astronomers at Kitt Peak National Observatory in Arizona, US originally spotted the asteroid on June 19, 2004. The asteroid was previously estimated to be 450 metres in diameter, roughly half the size of the 828-meter Burj Dubai, the world’s tallest man-made skyscraper. Later estimations put it at a far lower distance, around 370 metres, according to scientists.
Apophis is an Aten-class asteroid, which means its orbit intersects with Earth’s orbit around the Sun. Co-discoverers Dave Tholen and Roy Tucker were fans of Stargate SG-1, a science fantasy TV series in which the most notable villain was called Apophis, according to a 2005 report in Astronomy magazine.
Apophis would fly by Earth in April 13, 2029, at a height of less than 32,000 km. To give some perspective, the moon is at a distance of 384,400 km. It is indeed significant because it would be closer than many geostationary satellites which are 36,000 kms away from the Equator. Apophis will be the nearest an asteroid of this size has ever been. It will be so near that everybody in the Eastern Hemisphere, with or without observatories or telescopes, will be able to view it.
What was its route, and how likely was it to collide with Earth?
Apophis was the first asteroid in two years to receive a four-star rating on the Torino impact hazard scale. Many people were concerned that it would strike Earth given the proximity, mass, and velocity.
In 2029, a 340-meter-wide near-Earth asteroid called 99942 Apophis will cruise harmlessly by Earth, ~19,000 miles above the surface. See what #PlanetaryDefense scientists are doing now so they can take advantage of the opportunity this presents for science https://t.co/dyrLJDiBSN pic.twitter.com/pvr7Hqecwi
— Thomas Zurbuchen (@Dr_ThomasZ) May 1, 2019
Though from the start, the chances appeared solidly in position that such an event wouldn’t exist. But there were still grounds to suspect that an incident could occur. An asteroid may change its orbit if it passed through the keyhole at the correct time.
When Apophis was feared to collide with Earth in 2029, it was once anticipated that it would be able to fly through the keyhole. If it did, it was possible that its orbit would be changed, putting it on a collision trajectory with the planet in 2036. However, further analyses revealed that this was doubtful to have happened.