Extraterrestrial

Because Mercury does not have an atmosphere to play a role in insulation, so the temperature of the back side of Mercury can be as low as minus 172 degrees Celsius, and because of the proximity of the sun, the temperature of the sunny side of Mercury will soar to 432 degrees Celsius under the baking of the sun, so it can be seen that Mercury is simply a realistic version of the "world of ice and fire"

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

If you are so close to the main star in the solar system, life simply cannot survive

The milky way is a huge galaxy with hundreds of billions of stars, and the sun is just one of the less prominent stars that, along with many other stars in the galaxy, orbits the centre of the galaxy.

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

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

The solar system is located in a region with a stellar density of only 72 million parts per million of the highest stellar density region in the Milky Way, which is a remote and inhospitable part of the galaxy.

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

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

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