Extraterrestrial

After the sun evolves into a red giant, the hydrogen in its core is almost completely fused into helium, so the nuclear fusion inside the sun stops, after which the sun loses its internal radiation pressure and continues to collapse, leading to a constant increase in temperature and pressure in its core, while the helium in the central region of the sun is gradually compressed into the condensed state.

Although the Earth is just a "grain of dust suspended in the sun" in the universe, for us humans, this "grain of dust" is irreplaceable.

According to astronomers, Barnard's star is approaching the Sun at a rate of about 107 kilometers per second, and on this trend, it will arrive at a distance of 3.85 light-years from the Sun in 11800 AD, replacing Proxima as the closest star to the Sun

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

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?

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

The moon is the closest planet to the earth and the brightest and most easily observed object in the earth's night sky. Because the moon is always facing the same way towards the earth, for us humans living on earth, we can only ever observe one fixed side of the moon.

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

Intelligent life is rare in the universe, or perhaps it is just wishful thinking on our part. As mentioned earlier, just in the galaxy, there are hundreds of millions of planets that have the natural conditions to nurture life, so a reasonable speculation is that life has evolved on many planets, and even a number of planets have evolved intelligent life.