Why is Uranus also called a cold planet?

Uranus is one of the eight planets. It is a wood-like planet. Among the woody planets, it has the smallest mass and rotates almost horizontally around the sun. It is also called the cold planet. Why is Uranus also called a cold planet? Then let the constellation knowledge reveal the secret for everyone! Why is Uranus also called a cold planet? Of the nine planets, if Jupiter is called a hot planet, then Uranus is a cold planet. Although it is 1 times closer to the sun than Neptune, its surface temperature is the same as Neptune and not much higher than Pluto. By measuring its radiant energy, we know that only 6% of its radiant energy comes from the interior of the star, while Jupiter, Saturn and Neptune have 40%. It can be seen that Uranus is the only planet in the solar system that lacks internal heat energy. According to the current structure model of Uranus, its central temperature is only 2000℃ ~ 3000℃, which is much lower than other planets. In addition, there is a curtain with a thickness of about 10000 km outside its core. Unusually, this scene consists of water ice, ammonia ice and methane ice. If we want to fundamentally explain the cold of Uranus, we have to trace its origin and evolution history. According to its high ice content, accounting for 50% of the total mass, some people think that it is composed of countless comets, and comets are just cold and dirty snowballs. Uranus has a dim planetary ring system, which consists of dark particles about ten meters in diameter. He is the second ring system found in the solar system after Saturn's ring. It is known that Uranus ring has 13 rings, among which ε ring is the brightest and the others are dim. Uranus rings are as dark as Jupiter rings, but as big as Saturn rings. Uranus rings are considered very young. The differences between the gaps and opaque parts around the rings indicate that they were not formed at the same time as Uranus, and the materials in the rings may have come from satellites that were hit at high speed or shattered by tidal force. Most of the outermost five rings are ice cubes with a diameter of several meters to several tens of meters. In addition, Uranus may have a large number of narrow rings with a width of only 50 meters, and the ring reflectivity of a single ring is very low. The discovery date of the ring was1March, 977 10 in James II. Elliot Eduardo. Denham and Douglas. Mink used the Kuiper Airborne Observatory for observation. This discovery is very unexpected. Their original plan was to observe Uranus, covering SAO 158687, and study the atmosphere of Uranus. However, when they analyzed the observation data, they found that the star had briefly disappeared five times before and after the planetary coverage. They believe that there must be a ring system around the planet to explain it. Later, they discovered four other auras. Voyager 2 saw these rings directly when it flew over Uranus in 1986. Voyager 2 also discovered two new rings, increasing the number of rings to 1 1. From June 5438 to February 2005, Hubble Space Telescope detected a pair of blue rings that had never been found before. The outermost ring is twice as far away from Uranus as the previously known rings, so the newly discovered ring is called the outer ring of the ring system, which increases the number of Uranus rings to 13. Haber also discovered two new small satellites, among which Tianwei 26 also shared its orbit with the outermost ring. In April 2006, the image of the new ring released by Keck Observatory showed that the outer ring was blue and the other ring was red. One hypothesis that the color of the outer ring is blue is that it is composed of tiny ice particles of Tianwei 26, so it can scatter enough blue light. The inner ring of Uranus looks gray.