1846 On September 28th, Dr. Galle of Berlin Observatory in Germany received a letter. This letter was written to him by a young French mathematician, Le Ye Wei, asking him to aim his telescope at a specific sky at night. Le Ye Wei predicted that a new planet would be found there-the eighth planet in the solar system. Dr. Galle immediately picked up the accurate star map and started searching that night. After only half an hour's observation, he found a faint star in the sky, indicated by Le Ye Wei. After 24 hours of observation, it is confirmed that this star is constantly moving and is indeed an undiscovered planet. Revelle's prediction came true-the new planet was later named Neptune.
According to the prediction, Neptune is the first new planet discovered. There are nine planets in the solar system: Mercury, Venus, Mars, Jupiter and Saturn. People on earth can see them with their eyes, so human beings have known these five planets before history. The other three, Uranus, Neptune and Pluto, can only be seen through telescopes, so Uranus was not discovered until 178 1. Unlike Neptune, Uranus was discovered by accident.
Herschel, an English organist who likes stargazing, observed the starry sky with a telescope every night and stumbled upon this moving new star. At first, he thought he saw a comet. After many people calculated that the orbit of this star is almost a circle, he determined that it is also a planet orbiting the sun, so he named it Uranus.
The solar system has expanded by more than half.
After Uranus was discovered, many people aimed their telescopes at Uranus. Soon, its operation law was deduced for people. Uranus orbits the sun in a nearly circular orbit, with a radius of less than 2.9 billion kilometers and a speed of nearly 7 kilometers per second. Uranus' orbital radius is more than 19 times larger than that of the earth, and its running speed is slower than that of the earth, so it took 84 years and 9 months on the earth and only one year on Uranus.
Strange things followed. After 1800, the running speed of Uranus suddenly increased gradually, and when it reached 1830, its running speed was slower than usual. During the period from 1800 to 10, the journey of Uranus in space is much longer than that from 1830 to 1840. And in these years, Uranus has been out of the orbit of people's calculation, a little farther from the sun. In this case, there are other planets. If one planet is close to another, they will be slightly off track because of mutual attraction. When it approaches, the speed of planets with smaller orbits will be slightly accelerated; When the positive phase is far away, the speed of planets with smaller orbits will slow down slightly. Therefore, some people suspect that there is a new planet outside the orbit of Uranus that people have never seen before.
The new planet is farther than Uranus and definitely darker than Uranus. In the vast space, if you search blindly through a telescope, you may never find it. So some people calculate the position of this new planet according to the change of Uranus' running speed and orbit. Of course, calculation is not an easy task, and many complicated ones need to be applied.
Physical and mathematical formulas. 1845, a young British mathematician named Adams worked out this result and handed it over to the Royal Observatory. For some reason, the Royal Observatory put aside his calculation results and did not follow his instructions to search. The next year, Levell also calculated the results, and Caleb discovered the new planet-Neptune according to his calculation results.
Although Dr. Galle was the first person to see Neptune, the real achievement belongs to the person who calculated it. Therefore, everyone thinks that the honor of this discovery should belong to Adams and Levell. Because of their calculations, the radius of the solar system has expanded outward by 65.438+0.6 billion kilometers.
Distant world
The average distance from Neptune to the sun is 4.5 billion kilometers, which is more than 30 times farther than the earth. So the sun on Neptune is only the size of Venus seen on Earth. Neptune only receives 1/900 sunlight and heat per unit area. If the texture of Neptune's surface is similar to that of the earth, the temperature should be below -200℃ because there is too little sunlight.
Although Neptune's orbit is so large, it is slower than Uranus, less than 5.5 kilometers per second. By the time it goes around the sun, 165 years have passed on the earth. So Neptune, for example, has not been discovered by people on earth for more than a year.
On Neptune, although the years are so long, the months are surprisingly short. It is found that Neptune also has a satellite. People imagine that the moon on Neptune is exactly the same as the moon we see on earth, about the same size, but of course it is much darker. The moon revolves around Neptune at a very fast speed, and it takes less than 6 days to turn to the earth. The strangest thing is that the rotation direction of the moon is opposite to that of the earth.
Is Neptune itself spinning? This problem has not been solved so far. Because it is too far away, a telescope can't recognize the signs on its surface to study whether it is rotating. Some people say that Neptune rotates once every seven hours at 15 minutes. If this statement is correct, then after a day on earth, it has been nearly 4 days and nights on Neptune.
Neptune is about 50 thousand kilometers in diameter, 60 times larger than the earth. For Neptune, people only know a little about it now, because it is too far away from the earth.