How to determine whether an asteroid will collide with the earth?

The news that asteroids hit the earth is not uncommon, but many of them just passed by the earth and did not really hit the earth. So how can we determine whether an asteroid will collide with the earth? Then let's use constellation knowledge to reveal the answer! Let's have a look!

How to determine whether an asteroid will collide with the earth It is reported that when people search for "asteroids" in search engines, there will be a lot of news that "asteroids may collide with the earth". For example, "NASA warns that a killer asteroid with a diameter of 2 miles is heading for the earth", or "... the potential impact date is 2022" or "the tsunami caused by asteroid impact ... may destroy the American coast." And "... monster rock is flying to the earth at a speed of 17000 mph. "

These are just some news released in a short time. If you read these shocking headlines, you will usually find the most accurate information about asteroids, which definitely shows that asteroids will not hit the earth in a short time. Misleading headlines and reports use words used by scientists when talking about space objects and the meanings of some words in daily language.

For example, the phrases "near-Earth object" (NEO) and "potentially dangerous asteroid" (PHA) are astronomical terms used to classify celestial bodies with very specific definitions. If an asteroid is within 4.6 million miles of the Earth and has a certain brightness, it will be classified as PHA. This is actually just a way for astronomers to create a large number of noteworthy celestial bodies. Before naming an asteroid, no other assessment will be made to determine its "potential danger".

Near-Earth objects belong to a broader category. This is the general term for asteroids, comets and large meteoroids. Their orbits intersect with the Earth's orbit, which may cause collision danger.

Some news media warned of the arrival of the asteroid SF6 2006, which flew over the earth at a close distance, which certainly sounded like a sign of danger. However, in a list of "all celestial bodies with non-zero collision probability detected" maintained by the European Space Agency (ESA), searching for 2006SF6 and its catalog number 48 1394, nothing appears, which indicates that it does not seem to be included in 996544.

Next, the media continued to look at the asteroid public database maintained by the Near-Earth Research Center of NASA's Jet Propulsion Laboratory, and then obtained more information about SF6 in 2006. NASA estimated the asteroid's diameter at 965,438+09 to 2,690 feet (280 to 820 meters).

If you hit this space rock the size of a skyscraper, it may do some actual damage to the earth. However, in 2006, when SF6 was closest to the Earth, it was about 1 1.23 months, which was equivalent to about 2.7 million miles (4.3 million kilometers). So it poses almost no threat to the earth. However, some major threats may come from celestial bodies not listed in the list.

For example, at 20 13, a small celestial body fell and exploded over Russia, causing local injuries of about 1200. Space rocks were never observed before the explosion.

The technology used by astronomers has been improved to the point where recent celestial bodies are discovered every day. This includes some celestial bodies that are actually very close to the earth, but some of them are very small. If they really hit the earth, most of them may burn in the atmosphere.

The first step of simulating the response is to aim the astronomical telescope at the most threatening celestial body according to the preliminary calculation results, so as to accurately calculate its flight speed and trajectory; The second step is to formulate corresponding strategies: force the incoming celestial bodies to deflect, or evacuate the people in the threatened area as soon as possible? If the "enemy" is less than 50 meters in diameter, the current scientific knowledge is to evacuate the crowd. According to scientists, it is now possible to reach the area where asteroids will attack two weeks in advance; A few days in advance, the specific disaster area in Fiona Fang can be reduced to several hundred kilometers. To deal with larger celestial bodies, can we launch nuclear weapons to smash them like some science fiction movies? Scientists think this is the worst policy, because it may "break the whole into parts" and produce small but still dangerous celestial debris. At present, the accepted scheme is to launch a device to the target celestial body, forcing it to deviate from its original orbit, just like a "cosmic bumper car". NASA plans to do this "collision" experiment with a real celestial body with a diameter of150m in 2022. However, the "planetary defense" scheme discussed by the scientific community is really implemented, and there is a potential controversy, that is, "Who will make the decision?" Possible difficulties include whether developed countries are willing to sponsor such operations if they are not in the disaster area. Romana Coffler, an expert from the United Nations Office for Outer Space Affairs, said that "the current understanding is to shelve it".

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