If there is a sudden loud noise in the sky, you must be thinking, either the spring thunder is at work, or the sonic boom produced by human fighters when accelerating to supersonic speed, there have been many fighter sonic booms on the mainland, Henan, Chongqing, Hangzhou, Sichuan and Qinhuangdao have all appeared.
On the morning of April 27, EST, there was a loud noise and a series of fireballs over the southern United States, and many residents from Arkansas, Louisiana and Mississippi were frightened by the sight, and more than 30 people reported strange things they had seen.
There was an unknown noise and a series of fireballs in the United States
It is understood that the loud noise is neither a thunder explosion, nor a fighter sonic boom, but a large fireball from outer space, when it is flying at high speed in the atmosphere, the violent explosion produces a loud noise, disintegrating into a series of small fireballs, the instantaneous brightness is 10 times the full moon, and the ground is illuminated like daylight.
The Geosynchronous Lightning Mapping At the Marshall Space Flight Center in Huntsville, Alabama, captured the images and sounds, and Bill Cook, head of NASA's Office of Meteoroid Environment, said in surprise: "What makes me unusual is that more people hear loud noises than people see fireballs."
The fireball initially appeared in the sky 87 kilometers above the Mississippi River in Mississippi, moving southwest at an extremely fast speed, friction became more intense as the altitude decreased, and finally disintegrated in the sky about 55 kilometers above a swamp north of Minorca, Louisiana, creating a cascade of small fireballs.
According to one eyewitness, he first heard an unknown loud noise, then felt a distinct rumble, and the ground vibrated as he habitually looked up into the sky and found an orange fireball the size of a basketball flying in the direction of the Mississippi River to the west, with a white tail of flames behind it.
Crashing into Earth at the speed of a third universe?
Know how fast a fireball can crash into Earth? According to NASA's calculations, the speed of the fireball entering the atmosphere is 24.58 km / s, the speed of the Chinese space station around the earth is about 7.8 kilometers per second, and the speed of the fireball is about three times the speed of the Chinese space station.
Speaking of spacecraft speed, we have to mention the first cosmic speed, the second cosmic velocity and the third cosmic velocity, the first cosmic velocity is 7.9 km / s, which is the ultimate speed around the earth, and the spacecraft can only orbit around the earth for a long time if it reaches the first cosmic speed.
The second cosmic speed is 11.2 km / s, which is the ultimate speed of the spacecraft to completely get rid of the earth's gravity, and the spacecraft has a second cosmic speed to completely move away from the earth and enter the solar orbit, for example, the spacecraft wants to fly to Mars, and its own flight speed must reach at least 11.2 km / s.
The third cosmic speed is 16.7 km / s, which is the ultimate speed to get rid of the sun's gravitational pull, the spacecraft left the solar system through the third cosmic speed into interstellar space, the American Voyager 1 and Voyager 2 flight speed exceeded 16.7 km / s, many years ago has entered the interstellar space.
24.58 km / s, we look at the numbers, the fireball is completely at the third cosmic speed crashed into the earth, if not with the earth, with its flight speed can leave the solar system into interstellar space, is this really the case? Not necessarily.
Space flight, the most important thing is to choose a reference object, the first cosmic speed, the second cosmic velocity and the third cosmic velocity are all based on the earth as a reference, if it is to take the sun as a reference, the third cosmic speed is 42.10 km / s, just imagine, the earth's orbital speed is 29.79 km / s, the spacecraft to leave the solar system, it must be much faster than the earth's rotation speed.
The reference object of the fireball's speed of 24.58 km/s is the Earth, and there is a question here, if the reference is replaced by the sun, what is the actual flight speed of the fireball? The asteroid enters the atmosphere and rubs against the atmosphere to become a fireball, and there are three possibilities for the asteroid to meet the Earth.
First, the asteroid catches up with the earth from behind the earth, which means that the asteroid is faster than the third cosmic speed. Second, the asteroid and the earth meet at a certain angle, and the asteroid velocity cannot be determined, which may be less than the third cosmic velocity and may be greater than the third cosmic velocity. Third, the asteroid meets the Earth directly, indicating that the asteroid velocity is significantly less than the third cosmic velocity.
So, only if the asteroid catches up with Earth from behind can it be certain that the asteroid's velocity exceeds the third cosmic velocity, but there is no more evidence to support this possibility, so it is currently impossible to determine whether the actual velocity of the fireball reaches the third cosmic velocity of 42.10 km/s (the reference is the sun).
At last
The third cosmic speed of 16.7 km / s actually refers to the initial speed of launching a spacecraft from the earth, if the sun is used as a reference, then the third cosmic speed becomes 42.10 km / s, and the speed of the fireball crashing into the earth is 24.58 km / s may not reach the third cosmic speed. Interesting and informative scientific content, please pay attention to the only WeChat public account: Interesting Exploration