Our entire planet is shrouded in a dense layer of air. The name of this layer of Earth's atmosphere. The closer the air to the surface, so it is denser. Climbing up, you can feel how the air density decreases, it becomes sparse. And where ends the atmosphere and begins space - empty space.
Without the atmosphere on Earth, no life, because living beings there was nothing to breathe. Air shell affects the climate on the planet, protects the Earth from radiant solar heat and cosmic cold.
If the Earth was not covered by aerial shell, mankind has suffered from heaven shells - meteorites. Before falling to the earth, meteorites collide with the atmosphere, their flight is slowed down, they are red-hot and burn without causing earthlings harm.
The weight of the air was first measured by Galileo Galilei. And it happened 300 years ago. Took a great scholar metal ball made a hole in it weighed, the weight recorded. Then he pumped the air out of the ball, the hole tightly sealed and again put on the scales. And then everyone saw that the ball was noticeably easier.
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