Aug 08, 2022
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Astronomers discovered a large asteroid on a trajectory that may hit Earth but they assure us not to worry as the chances of a catastrophic impact is only one in 7,000.

Asteroid 2006 QV89 has a diameter of 164 feet and will make its closest pass to earth on September 9, 2019. The European Space Agency’s (ESA) estimates that it will pass a comfortable  4.2 million miles away from the Earth. This astronomical near-miss places QV89  at fourth place on the ESA’s “Risk List.” Though this sounds reassuring, it is the only object in the top 10 with a chance of impacting Earth this year. According to the ESA’s impact table, 2006 QV89 has a .014 percent chance of impacting Earth in September.

Scientists have known about the asteroid since it was discovered on August 29, 2006, by the Catalina Sky Survey located near Tuscon, Arizona.  It had two close approaches in the 1950s, then one in the 60s, another in the 70s and two more in the 80s. There were two more close approaches by 2006 QV89 in 2003 and in 2006. According to the ESA, after this year, it’s set for another close approach in 2032.

For comparison,  a meteor half the size of 2006 QV89 generated an airburst over Chelyabinsk, Russia, in 2013 and injured more than 1,100 people. The meteor was estimated to have an initial diameter of 17–20 meters and a mass of roughly 10,000 tons.

These close encounters are not uncommon. In 2006, a meteor struck in Norway with the blast force estimated at the equivalence of 100–500  tons of TNT, around 3 percent of Hiroshima’s yield. In September 2007, a meteor crashed in southeastern Peru. Many residents became ill, apparently from the noxious gases released from the impact.

Perhaps the most severe asteroid impact in modern history was the Tunguska event in 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened 770 square miles of forest, yet caused no known human casualties. The explosion is generally attributed to the air burst of a meteor since no impact crater has been found. The object is thought to have disintegrated at an altitude of 3 to 6 miles.Early estimates of the energy of the airburst range from 10–15 megatons of TNT or roughly 1,000 times greater than that of the atomic bomb dropped on Hiroshima, Japan. Studies have yielded different estimates of the meteoroid’s size, on the order of 200 to 620 feet.

NASA is beginning to seriously consider the threat of a catastrophic impact as a planet-threatening possibility. In April, scientists and civil authorities from around the world gathered at the International Academy of Astronautics 6th Planetary Defense Conference. in College Park, Maryland. Also, the National Near-Earth Object Preparedness Strategy and Action Plan was published by the White House in June 2018, describing plans for such an eventuality.

The Planetary Defense Coordination Office (PDCO) was established in 2016 to detect any potentially hazardous object. Since the PDCO was established, at least four major impacts have been reported. Only three impact events have been successfully predicted in advance, usually by only a few hours.  Currently, predictions are mainly based on cataloging asteroids years before they are due to impact. This works well for larger asteroids as they are easily seen from a long distance but is ineffective for predicting smaller objects that can still be quite destructive.