When the solar system was formed, there were countless other celestial bodies besides the eight planets we are familiar with, such as asteroids, comets and dwarf planets!
These celestial bodies are of various shapes and sizes, not just our common spheres! And their division is mainly concentrated in two places, one is the asteroid belt and the other is the Kuiper belt!
As we all know, the asteroid belt is a gathering place for small celestial bodies between the orbits of Mars and Jupiter. Its existence is like a dividing line, which contains four smaller rocky planets, including the earth. Outside the boundary, there are four giant gas giants like Jupiter!
Among them, Neptune is the farthest one! Its orbital radius has reached more than 30 astronomical units.
So 30 astronomical units is 4.5 billion kilometers! This distance, for our present technology, is an extremely distant place. Now, only Voyager 2 has visited Neptune's artificial detector!
Before the 20th century, people always thought that Neptune was the farthest celestial body in the solar system, and there were no other celestial bodies besides Neptune. So this is the end of the solar system!
However, in 1930, American astronomer Tom Bo discovered a celestial body farther than Neptune, namely Pluto, the ninth largest planet! This discovery led to the later Kuiper Belt.
Since the discovery of Pluto, astronomers at that time vaguely felt that there might be more than one celestial body besides Neptune!
195 1 year, according to the theory of the origin of the solar system, Dutch astronomer Gerard Kuiper thought that there might be many small celestial bodies around Neptune, which were the fragments left by the formation of the solar system. They are called circular distribution around Neptune, and the orbital radius is about 40AU to 50AU. This is the first time that the Kuiper belt has been proposed.
However, since it was put forward, the confirmation of Kuiper Belt was not confirmed until 1992. Therefore, the missions of Voyager 1 and Voyager 2, the farthest probes sent by human beings, have no plans to detect the Kuiper Belt, and their cameras were permanently turned off at 1990.
The main way to understand the Kuiper Belt basically depends on telescope observation, but only those celestial bodies with larger diameter and brightness, such as Venus and Venus, were discovered later! As for those small and dim celestial bodies, telescopes can do nothing. So we know nothing about what kind of small celestial bodies exist in the Kuiper Belt!
This situation was not changed until the launch of a detector in 2006! This detector is the New Horizon detector!
In June, 2006, 5438+ 10, NASA launched a probe named New Horizon. The mission of this detector is to go to the Kuiper belt 5 billion kilometers away for close detection. Nine years after launch, in July of 20 15, New Horizon reached its first detection target, namely Pluto!
The above photo was taken when the new horizon was about 450 thousand kilometers away from Pluto. This is the first time that humans have observed Pluto so closely! Its surface features are clearly visible. These detailed close-up photos,
These pictures give us an unprecedented understanding of the surface of Pluto! Besides Pluto, New Horizons also explored its moon Ka Rong!
The above photo was taken in Ka Rong, 470,000 kilometers away from Pluto, 65,438+00 hours before approaching Pluto. From this picture, we can see that the surface of Ka Rong is more complicated than Pluto, and its surface is covered with craters and cracks, as if it were a celestial body formed by the collision of multiple fragments.
After that, New Horizons flew to the depths of the Kuiper Belt. 20 19 10, it came to a place about 6 billion kilometers away from the earth, where it photographed a celestial body that we had never seen before.
The above picture was taken at a distance of about 16600 km from the new horizon surface, and the shooting time was 20 19 1. From the figure, we can see that this celestial body is shaped like a gourd, the diameter of its smaller part is about 16 km, the diameter of its larger part is about 20 km, and the overall length is about 20 km. This celestial body is marked as 20 14 MU69, and we call it Tianya Haijiao!
The ends of the earth are the farthest celestial bodies we have detected so far. Judging from its shape, it may be formed by the merger of two small celestial bodies, and the speed of merger should not be greater than 3 meters per second, because according to calculation and simulation, if it is greater than this speed, there will be no such obvious neck structure when the two celestial bodies merge!
As for why they formed such an alliance before the merger, it is still a mystery!
The whole color of the ends of the earth is reddish, which is caused by carbon-containing molecules exposed to ultraviolet rays for a long time, so this shows that the material composition of the ends of the earth contains organic molecules, and organic molecules are the key factors to form life, so detecting such a small celestial body may help us understand the mystery of the origin of life!
After flying over the ends of the earth, New Horizons continued to sail forward, heading for the depths of the Kuiper Belt! On 2021April 16, NASA released the news. According to its information, on this day, the distance from the new horizon to the earth has exceeded 50 astronomical units!
This is the distance reached by the fifth man-made detector after Voyager/KOOC-0/2 and Pioneer/KOOC-0/KOOC-0/. To commemorate this critical moment, New Vision took this photo.
This is a photo taken by Voyager 1 from a distance. Although Voyager 1 has already left, New Horizon still senses its existence by detecting electromagnetic signals. Perhaps, in the distant and silent space, they encourage each other like this!
Ok, that's all for this issue. I am Teng Bao, a creator of popular science who loves astronomy. Click on the home page to see more exciting videos.