The coldest planet among the nine planets.

First, at the International Astronomical Congress in 2006, Pluto was excluded from the planet. But people are still used to juxtaposing Pluto with the other eight planets as nine planets. Pluto is a lovely and special constellation. Besides being the smallest of the nine planets, it is also the coldest constellation. Why is Pluto so cold? Let's find out.

The temperature of the planet is mainly affected by the distance from the sun. The farther away from the sun, the lower the temperature. Pluto is the planet with the farthest distance from the sun and the smallest mass among the nine planets in the solar system. Pluto is limping in the cold and dark space 5.9 billion kilometers away from the sun. On Pluto, the sun looks like a bright star.

Pluto is the coldest planet discovered so far and the farthest planet from the sun discovered by human beings. Because Pluto is so far away from the sun, its surface temperature is almost close to MINUS 240 degrees Celsius. Because Pluto is so small and so far away, our understanding of it is limited: it is a rocky planet, and its surface may be covered with ice and frozen methane, whose boiling point is lower than that of liquid nitrogen.

In addition, Pluto is five times the mass of the earth and one of the farthest planets from the earth, about 28,000 light years away.