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The sun is so hot, why is the star closest to it not melting or burning?

Why are the planets closest to the sun not melting or burning?

Those planets that are closer to the sun than the Earth are indeed hotter than Earth, but this heat is not enough to melt the rocks that make up these planets!

Mercury is the closest rocky planet to the sun, and its temperature on the side facing the sun can reach 430 °C. Remember that 100 ° C is the boiling temperature of water, then 430 ° C is indeed a very hot temperature, in fact, this temperature can already melt some metals, such as lead.

However, Mercury is not composed of lead, it is composed of rock materials with a melting point of more than 600 °C.

So even though Mercury is really hot, it doesn’t heat up to the temperature it will melt, and it won’t heat up to boil or vaporize.


Mercury is the smallest and innermost planet in the solar system, and its orbital period around the Sun is about 87.97 days, the shortest of all planets in the solar system. It was named after Mercury by the god of Rome.

Mercury composite image of the messenger detector.

Like Venus, Mercury as an inner planet orbits the sun on the inside of the Earth. From Earth’s perspective, its angle with the sun never exceeds 28°. This distance from the sun means that the planet can only be observed in the evening or early morning near the western or eastern horizon. At this point it may look like a bright star object, but it is usually harder to observe than Venus. When Mercury is operating in orbit relative to the Earth’s inner side, a complete phase can be observed through a telescope, similar to the observation of Venus and the Moon, which is repeated in approximately every 116 days of the rendezvous cycle.

The messenger flew over the second image of Mercury. The Kuiper impact crater is located just in the center. The extensive ray system comes from the northern fast-impact pit near the top.

Mercury resonates with the Sun in a 3:2 spin orbit and rotates in a unique way in the solar system. Relative to other stars, it rotates three times around its own axis three times around the sun. Mercury from the perspective of the sun, in its own reference frame of the orbit of rotation and revolution, it rotates around the sun every two Mercury years, so for an observer on Mercury, two The year of Mercury is equivalent to one day.

The first Mercury false color image from the messenger.


The sun is the star in the center of the solar system. It is a near-perfect sphere of hot plasma with internal convection motion, which allows it to generate magnetic fields through power generation. It is by far the most important source of energy on Earth. It is about 1.39 million kilometers (864,000 miles) in diameter and 109 times the diameter of the Earth. Its mass is about 330,000 times that of the Earth, accounting for 99.86% of the total weight of the solar system. About three-quarters of the sun is made up of hydrogen (about 73%), and the rest is mainly helium (about 25%) and a small amount of heavy elements, including oxygen, carbon, helium and iron.

A C-3 flare (shown in the white area in the upper left corner) of the sun, a solar tsunami (a wavy structure visible in the upper right corner) and a plurality of filamentary lines of force exit the surface of the star.

Based on its spectral level, the sun is the G-type main sequence star (G2V). Therefore, it cannot be completely accurately called the yellow dwarf (its light is closer to white than yellow). The sun was formed by the gravitational pull of matter in the macromolecular cloud region about 4.6 billion years ago. Most of these materials are concentrated in the center, while the rest are scattered on a flat orbital disk, which forms the solar system. The material in the center becomes hot and dense, eventually leading to nuclear fusion at its core. This process is generally considered to be the formation of all stars.

This image was taken on January 12, 2007 using an optical telescope from Sunrise Satellite, showing the area where the natural plasma is connected to the fiber due to the polarity of the magnetic field.

Reference material

1.WJ Encyclopedia

2. Astronomical noun

3. theconversation

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