Why are X-rays absorbed in the atmosphere.

In summary, X-ray observations of outer space are typically done from orbiting platforms, while radio and optical astronomy is also effective. Despite higher energy electromagnetic radiation having the potential to penetrate more, Earth's atmosphere actually blocks the highest energy radiation (such as X-rays, gamma rays, and some UV) in the upper atmosphere, protecting us from genetic damage. Photoelectric absorption, Compton scattering, and pair production are the main mechanisms responsible for this absorption. Fortunately, this means that the atmosphere is optically thick enough to block high-energy radiation, even though it is relatively low-density.
  • #1
Naty1
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X-ray observations of outer space are usually made from orbiting platforms. Yet radio and optical astronomy seems to work pretty well.

I got to thinking that it seems odd for the highest energy electromagnetic radiation to be so well blocked by Earth's atmosphere...I would have thought: more energy the more radiation gets thru...but apparently not.

Seems like the highest energy radiation (X-rays,gamma rays, and some UV) from space are blocked in the upper atmosphere protecting us from genetic damage; I would have thought it would take more dense atmosphere to block the most energetic radiation; again, apparently not:

There is a nice diagram here:

http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg

What's the mechanism(s) that accounts for this absorption?? Is it the upper atmosphere that also blocks high energy radiation emitted from earth??
 
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  • #2
Photoelectric absorption, compton, pair production - the total extinction cross section for high-energy photons is large enough that the atmosphere is optically thick even though it's relatively low-density, because it's so deep. Lucky us. :smile:
 

FAQ: Why are X-rays absorbed in the atmosphere.

1. Why are X-rays used in medical imaging?

X-rays are used in medical imaging because they have high energy and short wavelengths, allowing them to pass through soft tissues in the body and create images of bones and other dense structures. This makes them useful for diagnosing injuries and illnesses.

2. How are X-rays produced?

X-rays are produced when high-speed electrons collide with a metal target, causing them to slow down and emit energy in the form of X-rays. This process is known as bremsstrahlung, or "braking radiation."

3. Why are X-rays absorbed in the atmosphere?

X-rays are absorbed in the atmosphere because they have high energy and can interact with molecules in the air. This can cause them to scatter or be absorbed by the molecules, making it difficult for X-rays to reach the Earth's surface.

4. How do X-rays affect living organisms?

X-rays can be harmful to living organisms because they can damage cells and DNA. However, in controlled doses, X-rays are also used in medical treatments such as radiation therapy to kill cancer cells.

5. Can X-rays pass through all materials?

No, X-rays cannot pass through all materials. The ability of X-rays to penetrate a material depends on its density and thickness. Dense materials like lead can block X-rays, while thinner and less dense materials like skin and muscles can be penetrated by them.

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