The linear velocity of Mercury's revolution is 47.87 km/s. According to the formula of gravitational potential energy, the escape velocity of the sun at the apohelion of Mercury's orbit can be calculated as follows:
mv^2/2=gmm/r；
v =√(2GM/r)= 6 1.8km/s；
That is to say, at the apohelion of Mercury, the speed of 6 1.8km/s can be completely separated from the solar gravity, and Mercury can't reach the escape condition, so it can only be attracted by the solar gravity.
However, the revolution speed of Mercury is also very fast. When mercury approaches the perihelion, it will be accelerated by the sun's gravity and then gradually move away from the sun. Therefore, the kinetic energy of mercury and the gravity of the sun are in a state of balance, so that mercury can only run around the sun, and can neither escape the gravity of the sun nor fall into the sun.
This is a photo of the transit of Mercury. Because of the earth's perspective, it seems that Mercury is very close to the sun, just like a sesame seed is only a few centimeters away from a watermelon. In fact, this is the illusion of perspective. The actual distance between mercury and the sun is the distance between mercury and the sun. For the sun, for the sun, Mercury is its satellite.
Moreover, the rotation and revolution of Mercury form the orbital vibration effect, which makes Mercury rotate three times for every revolution. Moreover, there is the precession effect of mercury, which causes the perihelion of the orbit to move forward a little every time mercury makes a revolution, which requires the perfect explanation of general relativity.