Massive Asteroid Apophis
Researchers at the University of Hawaii Institute for Astronomy (IfA) in the US, have announced that a large asteroid named ‘Apophis’ expected to pass extremely close or may hit the Earth in 2068 due to a phenomenon called Yarkovsky effect.
Apophis is set to make a series of visits over the coming decades, but the one that’s led to some breathless headlines at the moment is an anticipated close approach in 2068. The asteroid is estimated to be over 1,000 feet (300 meters) in size. That’s like having the Eiffel Tower fly through space.
Astronomers say they’ll have to keep an eye on the near-Earth asteroid Apophis to see how much of a danger the space rock poses to our planet during a close pass in 2068. But don’t panic: The chances of an impact still seem very low.
Since astronomers hadn’t measured this solar push on Apophis before, they didn’t take it into consideration when calculating the threat the asteroid poses to us in 2068.
Those previous calculations showed a tiny impact probability — around 1 in 150,000.
Massive Asteroid Apophis was first spotted in 2004 and scientists have been revising what we know about its path as more data is collected. In 2013, researchers determined it wouldn’t smack us in 2036.
A 2029 impact was also previously ruled out. Apophis will come in close on Friday, April 13, 2029, and should be visible from Earth with the naked eye. That visit should help astronomers dial in the asteroid’s future trajectory.
In the meantime, scientists are working on ways to deal with potentially dangerous asteroids. NASA’s DART mission, for example, will demonstrate a method that involves crashing a spacecraft into an asteroid’s moon in order to nudge it.
If that works, the concept could be used to push threatening asteroids onto safer paths. The uncertainty about Apophis is a little unsettling, but you shouldn’t pencil in the end times on your calendar just yet.
“Astronomers will know well before 2068 if there is any chance of an impact,” said the University of Hawaii. Sit tight. Scientists are keeping a close eye on it.
Now, a new study shows the asteroid is drifting away from its previously predicted orbit by about 557 feet (170 meters) a year due to the Yarkovsky effect, lead author and the University of Hawaii at Manoa astronomer David Tholen said.
“Basically, the heat that an asteroid radiates gives it a very tiny push,” he explained during a virtual meeting of the American Astronomical Society’s Division for Planetary Sciences.
“The warmer hemisphere [of the asteroid] would be pushing slightly more than the cooler hemisphere, and that causes the asteroid to drift away from what a purely gravitational orbit would predict,” Tholen said.
Fortunately, the asteroid will make a close (yet still safe) approach to our planet in 2029, allowing ground-based telescopes – including the Arecibo Observatory’s powerful radar dish – to get a more detailed look at the asteroid’s surface and shape.
Apophis will be so close it will be visible with the naked eye, at third magnitude — about as bright as the binary star Cor Caroli.
“Of all dates, Friday the 13th in April, April 13 [2029], is when the flyby will occur,” Tholen said., “Obviously, the 2029 close approach is critical.
We’ll know after that occurs exactly where it [Apophis] was as it passed the Earth, and that will make it much easier for us to predict future impact scenarios.”
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. (A milliarcsecond is a thousandth of an arcsecond, an angular measurement that helps scientists measure cosmic distances.)
“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.”
Tholen noted that Apophis has been troublesome for astronomers, with “numerous impact scenarios” predicted (and then largely ruled out) since it was first found in 2004.
For example: Initially, scientists calculated a 3% chance of Massive Asteroid Apophis slamming into our planet in 2029, a prediction Tholen said was quickly ruled out after more observations showed the true path of the little world.
If there’s any threat of an impact, astronomers will know long before 2068 how to approach the problem.
Engineers around the world are developing ideas about how to deflect dangerous asteroids from our planet, concepts that range from gravitational tugs to “kinetic impactors” that would knock an incoming rock off course.
A joint European-NASA mission will also test and observe asteroid deflection at a space rock called Didymos, starting in 2022.
If all goes to plan, NASA’s Double Asteroid Redirection Test (DART) spacecraft will slam into “Didymoon,” the moon orbiting Didymos.
The European Space Agency will then launch the Hera mission in 2023 or 2024 and reach Didymos two years later, to see how well the kinetic impactor did in moving the moon from its previous orbit.
NASA has a dedicated Planetary Defense Coordination Office that collects asteroid observations from a network of partner telescopes, and which runs through scenarios with other U.S. agencies for asteroid deflection or (in the worst case) evacuating threatened populations from an incoming space rock.
So far, decades of observations have found no imminent asteroid or comet threats to our planet.
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