Experts explain 'Where is the boundary between the universe and the sky?'

If you think carefully about the fact that the surface of the earth and the universe are connected without being separated by walls or membranes, some people will be scared of the sky. The Earth's atmosphere plays an important role in life, including protection from deadly cosmic radiation and water circulation, but it is only as thick as the skin of the Earth. Atmospheric and space experts explain the simple question of how far the sky of the earth is and where it is from the universe.

Where does Earth end and outer space begin? | Live Science

According to Katrina Bossart, a space physicist at Arizona State University, the density of the atmosphere decreases as it gets farther from the earth, and the composition changes so that light atoms and molecules dominate.

As the air pressure drops as the density of the atmosphere decreases, sudden changes in the altitude of the airplane also affect the eustachian tube , which is the thin tube that connects the ears and nose. Matthew Eiger, a professor of atmospheric science at the University of California, Davis, told the science news site Live Science, 'It's this change in air pressure that can hurt your ears when an airplane takes off.' I told you.

As the altitude rises and the air becomes thinner and thinner, ordinary airplanes cannot get lift and cannot fly. Bossart and Eiger believe that the boundary at which this plane cannot fly is the end of the Earth's atmosphere and the beginning of the universe.

The specific height at which an airplane cannot fly depends on various conditions, but many institutions in the aviation field are based on the

Karman line at an altitude of 100 km for convenience. This is named after Theodore von Kalman (Kerman in English), an aeronautical engineer from Hungary. That said, the Karman line isn't physical, so if someone reaches an altitude of 100km, nothing will change and you won't notice the Karman line, Eigel said.

The altitude of 100km is not only sharp, but also engineering. According to Bossart, the Karman Line is an approximate area that can orbit the Earth at least once without the satellites burning out or out of orbit. Of course, artificial satellites do not only orbit the earth once, so even artificial satellites that orbit the lowest region of the earth's low earth orbit fly at altitudes of 160 km or more and 1000 km or less. It will slow down, so it will be out of orbit in a few years.

Then, when asked, 'Does the atmosphere disappear when the altitude exceeds 1000 km?', That is not the case. 'To get rid of the traces of the Earth's atmosphere, we have to go tens of thousands of kilometers further. The outermost part of the Earth's atmosphere, the hydrogen atoms that form the geocorona , are from the moon. May also spread outwards. '

Airplanes can only fly up to 100km, but humans and birds flying in the air will reach their limits sooner. As it is known that when you climb a high mountain, water boils at a temperature lower than 100 degrees Celsius, when the atmospheric pressure drops, the temperature at which water turns into a gas also drops, and eventually it will boil even at body temperature. is.

Regarding this, Mr. Eiger said, 'In principle, even animals can go to the Karman line, but in reality, animals have a low air pressure as the liquid in the lungs boils. ) ”, You cannot survive at altitudes higher than that.”

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