"earth"

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.

In the past days, scientists have been working on the study of meteorites, and as the research continues, there is more and more evidence that life should originate from outer space

The earth's water resistance comes from the high temperature, pressure and density of its interior

The "Ryder" crater is actually located on the rim of a much larger crater. Exploration data show that this old crater is about 70 km in diameter, and its rim rises high above the inner area, with an altitude difference of about 3 km

The 500 trillion ton comet was discovered in 2010 by astronomers Pedro Bernardinelli and Gary Bernstein

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.

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

In orbit for longer and longer periods of time, we need to solve not only inorganic resupply problems such as food, water, oxygen and propellant, but also the various problems faced by astronauts flying in orbit for long periods of time

In our solar system, there are 2 planets in the habitable zone of the solar system, one of which is our home planet Earth, and the other is Mars

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