"earth"

In general, when a spacecraft, probe or rocket wreckage re-enters the atmosphere, they are fast, reaching several kilometers per second or even faster

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

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

The existence of reproductive isolation, so that these situations can not occur, even if there are some individuals of different species sometimes complete the mating, but they generally can not produce offspring, or produce offspring can not continue to reproduce

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

The earth has been spinning since its inception and has been doing so for 4.5 billion years now, so why has it not stopped yet?

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

Of all the known rocky planets in the solar system, the one with the most similar natural environment to Earth is Mars, and exploration data show that Mars also has an atmosphere, four seasons of the year, and even a rotation period similar to that of Earth.

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.

Prehistoric civilization have always been the talk of the town, and it's no wonder - after all, humans have been around for so short a time in the history of the planet that if we were to compress the history of the planet into a single day, then humans would probably only appear in the last two minutes of that day. In the past, there have been frequent claims of the discovery of suspected prehistoric civilization, the most notable of which would be a two-billion-year-old nuclear reactor.