On July 25, an asteroid with a diameter of about 57 meters to 130 meters passed the earth at a speed of 24.5 km / s. at the latest, it was only 74000 km away from the earth, equivalent to one fifth of the distance between the earth and the moon. Even more thrilling, the asteroid was not discovered by Brazil's sonal Observatory and NASA until the day before flying to earth, and was given the code 2019 OK.
Although experts have been tracking a large number of Neos, asteroids are not one of them. The asteroid was first discovered by the sonal Observatory in Brazil on July 24. Sonal Observatory posted on Facebook that 2019 OK is the largest asteroid closest to the earth this year. Its nearest distance from the earth is only 74000 km, equivalent to 0.19 earth month.
NASA then released a report on the asteroid, revealing that it was an Apollo asteroid. According to its tracking, the asteroid's orbit is very special. It moves rapidly along a strange elliptical orbit, so that it will be rapidly pushed into the orbit of Venus and Mars, and the retention time in the earth orbit is very short, which may be one of the reasons why astronomers have not found the asteroid.
Astronomers everywhere expressed their fear of this unexpected visitor.
Michael middot, associate professor of astronomy at Monash University, Australia; Brown said, "this is a disturbing approach. Professional institutions lack warnings about similar asteroids flying over the earth. Although this asteroid did not attack the earth, it is enough to show that this threat of impact is accelerating."
The asas-sn project team, an international telescope network headquartered at Ohio State University, posted the trajectory of the asteroid 2019 OK on twitter. It wrote in a follow-up tweet, 'if an asteroid of this size collides with the earth, it will cause very serious consequences, and the power of the impact will be equivalent to millions of tons of TNT, And will form a crater of about 1 km. "
2019 OK orbit source: asas-sn it is understood that if an asteroid of 2019 OK level really patronizes the earth, it will cause devastating disasters. The most influential asteroid attack in recent years occurred in Chelyabinsk, Russia, in 2013. An asteroid about 17 meters wide broke into the atmosphere over Russia. The shock wave damaged about 7200 houses, and more than 1500 people were injured by glass fragments caused by the explosion.
The earth encounters some asteroids every year. Although most of the time there are no risks, astronomers are always vigilant. At present, the United States has launched the defense plan for asteroids hitting the earth, cooperated with many countries to observe Neos, and listed asteroids with a diameter of more than 1 km as potential threat objects that can cause global impact for key observation and tracking. In February 2018, China joined the international asteroid early warning network approved by the United Nations as a full member. As the main equipment in this field in China, the purple Observatory near earth object telescope has also been committed to the observation and research of near earth objects.