Extraterrestrial

The Big Dipper is located in the constellation Ursa Major, and under good observing conditions, we can find them almost every day in the night sky of the Northern Hemisphere. These seven shining stars form a unique spoon shape that is very easy to recognize.

Whichever way you look at it, humans cannot be the only intelligent creatures in the universe. As far as we know, the universe has existed for at least tens of billions of years, so a reasonable speculation is that there is probably an advanced civilization in the universe that is hundreds of millions or even billions of years ahead of humans, and if that is the case, their level of technology is something that we humans simply cannot imagine.

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

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"

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

Titan is the largest moon of Saturn and the second largest in our solar system, even a little larger than Mercury, one of the eight planets. Due to tidal locking, Titan's rotation period and revolution period are the same, similar to our Moon

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

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

If a shot is fired at the moon from the space station, the bullet fired will be firmly bound by the earth's gravity and it will be impossible to hit the moon