The near-Earth asteroid Apophis might be more likely to strike Earth in 2069 than thought. Astronomers say they’ll have to keep an eye on it.
Astronomers first spotted asteroid Apophis back in 2004. Then, they found Apophis would pass near the Earth in 2029, 2036, and again in 2068. More studies concluded that it was highly unlikely that the asteroid will pose any threats to Earth.
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Now, a team of scientists from the University of Hawaii reported on the status of asteroid Apophis during a virtual meeting of the American Astronomical Society’s Division for Planetary Sciences. David Tholen, an astronomer at the University of Hawaii, talked about the research he and his team conducted regarding the path of the asteroid and the likelihood that it will strike Earth.
New research calculates that Apophis is likely to collide with our world in the year 2068.
Estimations show the asteroid is over 1,000 feet (300 meters) in size. That’s like having the Eiffel Tower fly through space.
The new study shows that earlier researchers had not accounted for the Yarkovsky acceleration by which the sun strikes one side of an asteroid. The result can be a tiny push in a certain direction which can change the asteroid’s path through space.
As the heat radiates away from the asteroid, a small amount of energy pushes back against the asteroid, forcing it to turn slightly. David Tholen, an astronomer at the University of Hawaii, and his team calculated that the Yarkovsky effect is pushing Apophis to one side enough to force it to drift by approximately 557 feet (170 meters) a year.
They next applied that bit of knowledge to the math describing Apophis’ orbit. They found that the drift is changing the asteroid’s course in a way that will bring it closer to Earth. The new calculations show that the asteroid indeed poses a threat to us in 2068. Tholen suggests that astronomers will have to keep an eye on Apophis as its rendezvous date approaches.
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“This acceleration arises from an extremely weak force on an object due to non-uniform thermal radiation,” the university said in a statement in late October. This is essentially a slight nudge due to the effects of sunlight, but it can change an asteroid’s path over time.
“The 2068 impact scenario is still in play,” Tholen said. “We need to track this asteroid very carefully.”
Tholen’s team made the discovery after four nights of observation in January and March with the Subaru Telescope, a Japanese optical-infrared telescope on the summit of Maunakea, Hawaii. The researchers collected 18 exposures of the asteroid at very high precision, with an error of only 10 milliarcseconds in each observation.
“We really nailed the position of this asteroid extremely well,” Tholen said. “That was enough to give us a strong detection of the Yarkovsky effect, which is something we’ve been expecting to see now for a while.”
In the upcoming approach, scientists expect Apophis to pass by at a distance of 31,200 kilometers (19,400 mi) from Earth’s surface on 13 April 2029. People will be able to see its passage with the naked eye. That visit should help astronomers dial in the asteroid’s future trajectory.
If there’s any threat of an impact, astronomers will know long before 2068 how to approach the problem. Engineers around the globe are developing ideas about how to deflect dangerous asteroids from our planet. They are working on concepts that range from gravitational tugs to “kinetic impactors” that would knock an incoming rock off course.