Extraterrestrial

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?

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.

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

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

Compared to radio messages sent by humans, this method seems to be more suitable for intelligent civilizations to announce their presence in the universe, because this method belongs to the "broadcast" in space, and intelligent civilizations in all directions can be observed

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

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.

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

Between the Earth and the Moon there exists a much more empty space than imagined, so what can be put down in this space?

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