400 meters in diameter! Will the star of destruction, which has changed its orbit many times, hit the earth in 2068?

Under the protection of science and technology, there is basically no external force that can pose a threat to human beings except human beings, and the future threat will come from outside the earth.

Although many people know that the earth under their feet is just a trivial grain of sand in the universe, most people don't accept this fact from the bottom of their hearts. After all, the last disaster caused by external forces was 65 million years ago. In the extremely limited history of mankind, disasters are more natural and man-made disasters on earth than "cosmic disasters and alien disasters" outside the earth.

Fortunately, there are still a group of people looking up at the stars. They are very aware of the dangers of space and understand that the current "quiet years" are only a short-term "dynamic balance" in the universe. Maybe the radiation from Betelgeuse supernova explosion will reach the earth in the next second, or an asteroid will suddenly exceed the warning threshold and hit the earth.

In a word, our universe is a moving universe, and countless celestial bodies and cosmic phenomena and possible alien civilizations may change the fate of the earth and mankind in the next second.

Although the planets in the solar system, including the earth, have basically cleared the small celestial bodies in their orbits, the solar system advertised as "vacuum" is actually full of dust particles that are difficult to distinguish with the naked eye. Only the earth absorbs millions of tons of dust particles from space every year, but they are too small to reach the surface of the earth, which can really pose a substantial threat to the earth and human beings. Only those asteroids made of rocks and metals with a diameter of several meters to dozens of kilometers look back at the life history of the whole earth. These uninvited guests from outer space will always be the "sword of Damocles" hanging over the life of the earth, and no one knows when they will suddenly fall down.

In the inner solar system where the earth is located, asteroids are mainly distributed in the asteroid belt between Mars and Jupiter. However, under the influence of the gravitational perturbation of Jupiter, the largest planet in the solar system, asteroids often break away from the asteroid belt and become "wandering asteroids", and then have orbits similar to those of the Earth in the solar system.

So we can often see the news that astronomers have discovered an asteroid, and skip this asteroid, which is only "xx million kilometers" away from the earth. Moreover, there are many "Monday morning quarterback" news that attract people's attention. Over time, many people have an illusion that asteroids seem to revolve around the earth and have never had "close contact".

In the first 20 years of 2 1 century, there were 26 asteroid impacts witnessed and recorded by humans alone, such as the one in Chelyabinsk, Russia, which was widely reported that year. However, because the area where human beings live only accounts for a small part of the total surface area of the earth, there must be some meteorites falling on the sea or in uninhabited areas.

From the point of view of speed and quality, considering the "abrasion" of asteroids to the earth's atmosphere, an asteroid with a final diameter less than 1000 meters will be enough to destroy several blocks, an asteroid with a diameter of 500 meters to1000 meters will be enough to destroy a city, and an asteroid with a diameter of several kilometers to dozens of kilometers will cause disasters and secondary disasters on a global scale, and may even be.

In order to "keep asteroids out of the earth" as much as possible, astronomical institutions in various countries, mainly NASA, have been monitoring asteroids around the earth. NASA's "Sentinel Telescope" even produced an "asteroid risk list", among which the top three were 1950DA asteroid, Benu asteroid and destroyer.

When this destructive star was first discovered on June 19, 2004, astronomers calculated that it would arrive near the Earth at 4: 49 on April 14, 2029, when the collision probability was 2.7%. However, with the continuous supplement of tracking data in the later period, the probability of it hitting the earth in 2029 is reduced to 0.000 18%, and it will only approach the earth once every seven years due to destruction. In the latest deduction of NASA this year, the time when the destroyer may hit the earth has become 2068, and the probability is150,000.

The time and probability that the destroyer may hit the earth change again and again because of the existence of the Yarkovsky effect. Simply put, the uneven radiation of asteroids when absorbing and releasing heat will lead to slight changes in speed and direction, and the orbit will change after a long time, which will eventually lead astronomers to be unable to accurately predict the future orbital state of asteroids.

No matter in 2029 or 2068, as long as destructive stars still exist, they are a threat to the earth. If this destructive star with a diameter of 400 meters really hits the earth one day in the future, its explosive power will reach 654.38+0.53 billion tons of TNT, which is equivalent to 30 hydrogen bombs of the former Soviet Tsar to attack the city. Why not destroy it?

During his lifetime, the late physicist Hawking repeatedly called on mankind to open up a "second hometown" outside the earth as soon as possible, such as the moon or Mars. At present, Musk, who tested positive in COVID-19, is gradually achieving his ultimate goal of "emigrating to Mars".

On the occasion of the launch of Chang 'e V, I hope that human civilization will enter space as soon as possible, enter a wider Xinghai and write its own story in the vast universe.