Extraterrestrial

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

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.

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?

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

The universe is so big, but man's range is so small that the furthest man has been so far is the moon, which is only 380,000 km away from earth on average. Of course, humans have also launched all kinds of probes, and if you include them, the range of human activities is much larger.

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.

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

The energy released by the sun's nuclear fusion reaction, in addition to making the sun shine and heat, there is an important role, that is, to resist its own gravity

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.

Harrison Schmitt is the world's twelfth human to set foot on the lunar surface and the only scientist to have landed on the moon. On the 50th anniversary of the first human landing on the moon in June 2019, he warns that many people may be allergic to the dust on the lunar surface