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.

So far, we have not found any trace of life on Mars. No one knows whether there is life on Mars. However, when we are exploring Mars, sometimes we will see some interesting scenes, even some garbage. It is strange that there is no one on Mars. Why is there garbage? Where does this rubbish come from?

Like Earth, Titan has a nitrogen-rich atmosphere, with 98.44% of its atmosphere being nitrogen, making it the only nitrogen-rich planet in the solar system other than Earth.

In the Milky Way, the closest stars to the Sun are 4.22 light years away

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

This exoplanet, known as TOI 700d, is about 101.5 light years away from our Earth, which means that even if we were to travel to this exoplanet in a light-speed spacecraft, it would take at least 101.5 years of flight to reach it, so it is very far away

Data returned by the Odyssey Mars Rover suggest that these slope streaks are generally found on the sides of hills and mountains in Martian craters, and that their formation may be caused by frost formed by carbon dioxide at low temperatures

Ever since humans began to look up at the stars, they have been curious about the vastness of the universe, and this is still the case today. With the help of various observation devices, modern humans can take a large number of photos of the deep space of the universe, which are updated almost every day.

At the time of the "family photo" of the solar system, the Voyager 1 probe has reached a distance of 6.4 billion kilometers from Earth, very distant, so in the view of the Voyager 1 probe, the solar system, the major celestial bodies are very small

It has been billions of years since life appeared on earth, and although there are seven planets in our solar system in addition to earth, as well as a number of dwarf planets, moons and other relatively large bodies, so far we have not found alien life on any other planet in our solar system for the time being. Even mars, another earth-like planet in the habitable zone of our solar system, has not found a single sign of life. Could it be that life on earth is really unique and no other planet is allowed to have life?