"earth"

In this 5.5 million-year-old cave, not only is there no sunlight, but the environment is also very harsh

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

NASA's Jet Propulsion Laboratory's Near Earth Object Research Center has such a database, which is called the "Fireball Database."

Since the discovery of the first exoplanet in the 1990s, scientists have found more than 4,000 exoplanets, some like the giant gas planets of our solar system, and others like earth-like planets. Some exoplanets may have very harsh environments, perhaps as hot as venus or mercury, or as extremely cold as other planets. Of course there are also exoplanets that may have relatively suitable temperatures, may be located in the habitable zone of a star system, are a potentially habitable planet, and may even be a living planet.

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.

Although we do not know much about these two "super Earths" yet, but from the basic situation, these two "super Earths" are not suitable for human habitation

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?

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.

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

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