eli5 why does riding in an airplane cause radiation exposure? Does the airplane itself not block it?
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The atmosphere blocks out cosmic rays. When you’re flying in a plane, you’re high up in the air where the atmosphere is only about 1/3 as thick as it is at sea level. Less atmosphere = less protection from cosmic rays and to a lesser extent, solar particle radiation. The plane itself doesn’t offer appreciable protection from this radiation.
Just to be clear though, the radiation exposure is *extremely* minimal. The average flyer shouldn’t even bother thinking about it. The only people who should consider it (but certainly not worry about it) are flight crew members who spend decades flying for their jobs.
The airplane walls are pretty thin and made from a light metal, so no, they don’t block much radiation. This exposure is very low though, because the Earth’s magnetic field blocks most of space radiation anyway. Radiation exposure on interplanetary space missions is a whole other deal though.
Basically, 10 km of air blocks radiation better than a few cm of aircraft hull. A square metre of air by 10 000 metres is going to weigh several tonnes but a square metre of aircraft hull will only be a few kilograms. Remember, a cubic metre of air at sea level weighs a kilogram.
The atmosphere blocks most of the radiation from space. So if there’s less atmosphere above you, you’ll be exposed to more radiation. And the plane does block it. But you’ll still be exposed to slightly higher levels than when you’re on the ground.
Basically, 10 km of air blocks radiation better than a few cm of aircraft hull. A square metre of air by 10 000 metres is going to weigh several tonnes but a square metre of aircraft hull will only be a few kilograms. Remember, a cubic metre of air at sea level weighs a kilogram.
The skin of the plane does block some radiation. If you’re talking about the amount of material between you and space, The increase in altitude removes more of that barrier than the skin of the plane adds. To give an idea, the mass of air directly above a point at sea level is equivalent to the mass of a 12 foot column of solid aluminum. At cruising altitude, you are above most of the mass of the atmosphere and have only added a few centimeters of plastic and aluminum from the plane.
The skin of the plane does block some radiation. If you’re talking about the amount of material between you and space, The increase in altitude removes more of that barrier than the skin of the plane adds. To give an idea, the mass of air directly above a point at sea level is equivalent to the mass of a 12 foot column of solid aluminum. At cruising altitude, you are above most of the mass of the atmosphere and have only added a few centimeters of plastic and aluminum from the plane.
The skin of the plane does block some radiation. If you’re talking about the amount of material between you and space, The increase in altitude removes more of that barrier than the skin of the plane adds. To give an idea, the mass of air directly above a point at sea level is equivalent to the mass of a 12 foot column of solid aluminum. At cruising altitude, you are above most of the mass of the atmosphere and have only added a few centimeters of plastic and aluminum from the plane.
Mass blocks radiation, and planes are intentionally built to be as light as possible. If you’re using thin aluminum, it won’t block anywhere near as much radiation as something like lead would. The lead is heavier because it’s more dense, because it has more mass.
Air has a surprisingly large amount of mass when you consider how tall the sky is. So it does a pretty good job of blocking radiation before it hits the ground. The thin aluminum sheet from the plane won’t make up for all of the air that you’re “above” when flying.
Mass blocks radiation, and planes are intentionally built to be as light as possible. If you’re using thin aluminum, it won’t block anywhere near as much radiation as something like lead would. The lead is heavier because it’s more dense, because it has more mass.
Air has a surprisingly large amount of mass when you consider how tall the sky is. So it does a pretty good job of blocking radiation before it hits the ground. The thin aluminum sheet from the plane won’t make up for all of the air that you’re “above” when flying.
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