The so-called gravitational equilibrium surface refers to the surface formed by the same point of gravity. On Earth, we call the gravitational equilibrium surface that coincides with the stationary ocean surface the "geodetic level", which is actually equivalent to what we often call sea level.

In our universe, whether as large as a galaxy or as small as an electron, we are always in motion, and even when we think we are sitting motionless in our chairs, the earth is carrying us around the sun at a speed of about 30 kilometres per second, and the sun is also in motion, in fact it is carrying the entire solar system around the centre of the milky way, and at a speed of about 220 kilometres per second.

The sun, which we call the 'source of all things', has been sending light and heat to the earth for the past 4.6 billion years, which is why the earth is such a vibrant planet.What exactly does the sun use as fuel and how has it been able to burn for 4.6 billion years without going out?

This satellite is the communications satellite LES-1. In the 1960s and 1970s, the United States launched several such communications satellites, from LES-1 to LES-9, which were relatively small, weighing only about 32 kg, each with a horn antenna and an x-band transponder, as well as a 237 MHz signal transmitter, which were powered mainly by solar panels

According to our knowledge of known life, liquid water is essential for life. In other words, if there is liquid water on a planet, there is a possibility of life, and it is for this reason that scientists always consider liquid water as the first requirement when assessing the possibility of life on a planet.

The milky way is a huge galaxy with hundreds of billions of stars, and the sun is just one of the less prominent stars that, along with many other stars in the galaxy, orbits the centre of the galaxy.

There are many rumors that Pluto is a terrible world, where the temperature is so low that no life can survive, and even if there is life, it may be some extreme virus, so how terrible and unusual is Pluto?

If a shot is fired at the moon from the space station, the bullet fired will be firmly bound by the earth's gravity and it will be impossible to hit the moon

Below the solar system, there is a star system labeled "alpha Centauri".

Compared to iron, those rare earth elements in the universe, which are heavier than iron, are even rarer