Astronomers following the so-called doomsday asteroid Apophis have found that the rock is much larger than previously assumed. Since the asteroid could hit Earth in 2036, this is a significant concern.
The asteroid, named after an Egyptian god of chaos, darkness, and destruction, was initially thought to be around 885 feet (270 meters) wide, with a margin of error of a couple of hundred feet (60 meters). However, as Apophis approached Earth during its last pass, astronomers at the Herschel Space Observatory made new observations and concluded that its size and mass had been seriously underestimated.
“The 20 percent increase in diameter, from 270 to 325 meters, translates into a 75 percent increase in our estimates of the asteroid’s volume or mass,” said Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.
These numbers are preliminary estimates based solely on the Herschel measurements, and ongoing ground-based campaigns may yield additional information that could refine these results.
Moreover, the asteroid has a significantly different reflectivity, or albedo, than previously thought, measuring 0.23 instead of the earlier estimate of 0.33. This alteration affects astronomers’ calculations of the Yarkovsky effect, which describes how the Sun’s heating and cooling influence the asteroid’s orbital path.
Apophis raised alarms on Christmas Eve 2004, when a report suggested a 2.7 percent chance of impacting Earth in 2029. Even if it missed, that encounter could set it up for another strike in 2036. The asteroid briefly topped the Torino Scale of risk, reaching level four out of ten, where zero indicates no threat and ten signifies certain doom.
After further analysis and eliminating false reports, Apophis was downgraded to a level one threat and is currently expected to pass by on Friday, April 13, 2029, at a distance of about 36,000 kilometers, just inside the orbit of geostationary satellites. However, if the asteroid passes through a specific gravitational zone, it could alter its trajectory enough to likely collide with Earth on April 13, 2036. According to Neil deGrasse Tyson, if it passes through the center of this gravitational “keyhole,” it could strike the Pacific Ocean off Santa Monica, California, potentially causing devastating tsunamis along the Western seaboard.
Fortunately, NASA scientists at the Jet Propulsion Laboratory in Pasadena, California, have effectively ruled out the possibility of Apophis impacting Earth during the close flyby in 2036. They utilized updated information from NASA-supported telescopes in 2011 and 2012, along with new data from Apophis’ distant Earth flyby on January 9.
“With the new data provided by the Magdalena Ridge optical observatories, along with very recent data from the Goldstone Solar System Radar, we have effectively ruled out the possibility of an Earth impact by Apophis in 2036,” stated Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL.
Thus, for now, Earth remains safe from Apophis.
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