Typically, satellites that are in low Earth orbit - a classification that tends to be given to satellites at an altitude of less than 621 miles (1,000 km) but sometimes as low as 99 miles (160 km) above Earth, according to the European Space Agency (opens in new tab) - will fall out of orbit after a few years, Bossert said, due to "drag from the Earth's upper atmosphere gradually slowing down orbital speed." Various factors, such as the satellite's size and shape, play a part in determining how much air resistance it will experience and, consequently, its ability to orbit Earth successfully, according to Bossert. "Therein lies the sense one should have for the Kármán line: It is an imaginary but practical threshold between air travel and space travel," he said. "It is possible for something to orbit the Earth at altitudes below the Kármán line, but it would require extremely high orbital velocity, which would be hard to maintain due to friction. "It is typically defined as 100 kilometers above Earth," Igel added. "The Kármán line is an approximate region that denotes the altitude above which satellites will be able to orbit the Earth without burning up or falling out of orbit before circling Earth at least once," Bossert said.
Earth from space how to#
This line, given it marks the boundary between Earth and space, not only denotes where an aircraft's limits lie, but is also crucial for scientists and engineers when figuring out how to keep spacecraft and satellites orbiting Earth successfully. It's known as the Kármán line, named after Theodore von Kármán, a Hungarian American physicist who, in 1957, became the first person to attempt to define the boundary between Earth and outer space, according to EarthSky (opens in new tab). This is the area scientists have decreed marks our atmosphere's end, and space's beginning. "This is why your ears may pop during takeoff in an airplane," said Matthew Igel, an adjunct professor of atmospheric science at the University of California, Davis.Įventually, the air becomes too thin for conventional aircraft to fly at all, with such craft not able to generate enough lift.
Even though commercial planes have pressurized cabins, rapid changes in altitude can affect the slim eustachian tubes (opens in new tab) connecting the ear with the nose and throat. "The composition also changes, and lighter atoms and molecules begin to dominate, while heavy molecules remain closer to the Earth's surface."Īs you move up in the atmosphere, the pressure, or the weight of the atmosphere above you, weakens rapidly. "As you get farther from Earth, the atmosphere becomes less dense," Katrina Bossert, a space physicist at Arizona State University, told Live Science in an email.
0 kommentar(er)
