Extraterrestrial

An in-depth analysis of the light from these quasars using the Hubble telescope has shown that the Andromeda galaxy's "halo" has two nested gas shells, with the "inner shell" extending outward by about 500,000 light-years and the "outer shell" extending by up to 2 million light-years

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

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 mass of a star cannot grow indefinitely, it can only reach the "Eddington limit" at most, so beyond this threshold, it will soon "eject" the extra material

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

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 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.