Asteroids will rub shoulders with the earth again! Dinosaur： You scared me.
According to foreign media reports, NASA said that five asteroids will pass by the earth in the future, and one of them may be very close to the earth. It is reported that the smallest diameter of these asteroids is only 8 meters and the largest is 90 meters, and lular distance from the Earth will be as short as five distance to the moon.
A distance to the moon refers to the distance between the earth and the moon, which is about 238,900 miles (384,000 kilometers). It sounds like a long distance, but it is a very close distance in the vast space, and they will pass by the edge of the earth. Fortunately, the closest asteroid to the earth this time is smaller in diameter and will not pose too much threat to the earth.
Where are the asteroids?
Asteroids are celestial bodies in the solar system that move around the sun like planets, but are much smaller in size and mass than planets. Most of them are influenced by the gravitational force of the sun and Jupiter, and they gather in the asteroid-intensive area between the orbits of Mars and Jupiter. According to the statistics of 120,437 asteroids that have been numbered, this hotbed of asteroid "life" is composed of more than 500,000 asteroids. So many of them are called "main belt" and many people are used to calling it "asteroid belt".
The so-called "near-earth asteroids" can be understood very well just by looking at the literal meaning. "Near-earth" means that their orbits are very close to the earth, and they are a special group that deviates from the main belt.
Dangerous asteroid
According to analysis, only asteroids with a diameter of more than 140 meters and a minimum distance from the Earth of less than 0.05 astronomical unit (about 7.4 million kilometers) will be included in the list of dangerous asteroids.
According to the latest release of the website of the International Asteroid Center, researchers have discovered 1,640 "potentially threatening near-Earth asteroids" through global joint survey.
History of asteroid impact on the earth
As early as 65 million years ago, dinosaurs, a large animal that dominated the earth for 150 million years, suddenly disappeared. Astronomers speculate that there are two possible reasons for the extinction of dinosaurs: first, the explosion of supernovae, which is equivalent to about 10.24 hydrogen bombs, led to the extinction of dinosaurs; The second is asteroid impact. In 1978, American astronomer Luis Alvarez speculated that an asteroid hit Iceland, and this impact was equivalent to the energy of 1 trillion tons of TNT. Such a violent impact led to the disappearance of dinosaurs.
In addition, on June 30, 1908, a huge flash of light lit up the sky in the Tunguska River Basin in Shiquan, krasnoyarskiy kray, Siberia, followed by a violent explosion equivalent to 1,000 atomic bombs. A mushroom-like cloud of smoke soared 12 miles into the sky, and the scorching air billow swept the vast Taiga forest one after another, and hundreds of square kilometers of forest were destroyed in the explosion. This famous explosion was the Tunguska Big Bang.
In addition, according to the latest research report of geoscientists from the Australian National University (ANU), at least three asteroids with a diameter of 20-50 kilometers collided with the earth 3.2 billion years ago, which greatly changed the structure and elemental composition of the earth’s surface.
In recent years, scientists predict that an asteroid named Apophis will pass by the Earth in 2029 and hit the Earth in 2036. If it hits the earth, it will generate energy equivalent to the explosion of 110,000 atomic bombs, which is equivalent to the instantaneous destruction of the whole city of new york and its surrounding areas. If it hits the ocean, it will cause a devastating tsunami, which is more violent than the 2004 Indian Ocean tsunami.
Apophis is one of nearly 800 potentially threatening asteroids known to astronomers.
Prevent collision and defend the earth
In order to cope with this possible impact, some people put forward a plan to destroy asteroids with nuclear weapons. However, all the accumulated nuclear weapons on the earth are only enough to blow up an asteroid with a diameter of 9 kilometers, and they have to hit the center accurately. In addition, the consequences of a nuclear explosion in the universe are unpredictable.
Therefore, people are also considering other plans to deal with asteroids, such as using lasers or lead ingots. NASA is going to lure Apophis away with a "gravity trailer" when it flies to the Earth in 2029. When the asteroid passes near the Earth in 2029, it only needs to launch a "gravity trailer" spacecraft weighing about 1 ton, which can change the orbit of this asteroid. According to astronomers’ calculations, Apophis will slightly change its orbit when it flies over the earth this time, but when it returns again in 2036, the possibility of colliding with the earth is very small, only 1 in 5,000.
Although the speculation about the extinction of dinosaurs makes the prediction of the impact of asteroids on the earth scary, with the development of science and technology, from not knowing what asteroids are to accurately understanding and then boldly predicting, the progress of civilization makes us believe in the power of science, and there must always be a perfect way to deal with this "uninvited guest".
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Produced by: Tianjin science and technology hall Xu Wen, Beijing Normal University Zhang Tongjie.
Producer: computer network information center