We are on the earth, and the earth is in the solar system. What we can contact are basically things in the solar system, but the solar system is not a closed whole. Small celestial bodies between the stars can also travel freely. Some small celestial bodies from outside the solar system can even come to our earth.
In the latest issue of the Journal of Astrophysics, astronomers at Harvard University in the United States published a paper saying that they discovered the earliest known "interstellar visitor" on Earth. It arrived eight years ago in 2014. It was a meteor that broke into the Earth's atmosphere on January 8 of that year. Its number is CNEOS2014-01-08. Astronomers used image recordings to accurately calculate its orbit and velocity. It believed that it belongs to a small celestial body outside the solar system and came from another star system.
Speaking of visiting celestial bodies outside the solar system, many friends who like astronomy know the famous asteroid " Aomumo ". Astronomers first discovered it on October 19, 2017. This slender cigar-like small celestial body about 400 meters long and 40 meters wide rushed into the core area of the solar system at a speed of about 26 kilometers per second, with the direction almost perpendicular to the ecliptic plane of the solar system. To this day, many people still suspect that this unknown object is an alien warship.
At that time, it was considered the first interstellar small object to break into the solar system. However, in the past eight years, scientists have also discovered other small objects to break into the solar system, such as the 0.5-kilometer-wide comet "Borisov" that visited the earth in 2018, which is larger than Oumuamu!
However, the small celestial body that entered the earth, numbered CNEOS2014-01-08, is much smaller in size. Astronomers believe that its diameter is only 0.5 meters, as big as a trolley box, which is insignificant, but its speed is extremely fast. Its speed when entering the earth's atmosphere is as high as 216,000 kilometers per hour, and it can fly 60 kilometers per second, which is more than 176 times the speed of sound on the surface. It can penetrate the earth's atmosphere from top to bottom in two or three seconds.
of course has great kinetic energy, so although its mass is not large, it still bursts out extremely strong light when it hits the atmosphere. However, it is precisely the extremely strong light that it erupts when it enters the atmosphere that is monitored by the detection satellite in space, and can calculate its speed and judge its orbit through time, thus concluding that this asteroid is not a celestial body in the solar system.
So where did this meteoroid go after entering the atmosphere? In fact, it exploded and disappeared in the atmosphere almost instantly, and could not hit the ground at all, so the traces you want to find are basically impossible to find.
Why can we draw the conclusion that this small celestial body comes from outside the solar system through the speed at which it enters the atmosphere? Here we must talk about the third cosmic speed of . When an object on the earth can fly from outside the solar system to 16.7 kilometers per second, it can fly out of the solar system and eventually fly into interstellar space without the constraints of the sun's gravity, so it is often called the solar system escape speed.
It is obvious that the speed of the small celestial body numbered CNEOS2014-01-08 is far higher than this speed. The gravity of the celestial body in the solar system cannot accelerate it to near the Earth position, and the gravity of the sun cannot bind it not to leave the solar system. Therefore, it is judged that this small celestial body is a "interstellar visitor". Scientists also believe that this type of small celestial body is likely to be related to the birth of life in the early stages of the solar system.
In fact, there are many "interstellar visitors" like this in the solar system. However, humans have only discovered three of them at present. The earliest known meteoroids are CNEOS2014-01-08. However, since the formation of the solar system, such small interstellar celestial bodies have been constantly shuttled into the solar system. Now, many of them are shuttled into the inner solar system every day, but most of them are very small in size and difficult to find.
Reference:
"Science and Technology Daily" November 9th article "The first known interstellar visitor on the earth is confirmed"
