A world is a space: the area belonging to a planet, or the space between heaven and earth, is called a world.
A world may be covered with mountains or basins, or it may be filled with oceans of every kind.
Worlds come in many forms. Some teem with life, like the blue planet Earth, where we live.
Others are dead and silent, unable to support the reproduction of living things. They are either unbearably cold or unbearably hot.
In the boundless universe, Earth is an insignificant planet, yet it supports tens of millions of living things.
How many planets like Earth, each supporting millions of life forms, are there in the universe? This question remains a mystery to humanity.
So how many kinds of humans are there in the universe, and what do they look like? Why have we never seen them? Have they gone extinct?
Where do the gods people talk about come from? Are they visitors from beyond the stars? This book conceals ten thousand questions about the universe. Read on to find out.
