Which type of high-energy radiation emitted by celestial objects is completely absorbed by the atmosphere, necessitating space observation?

Answer

X-ray radiation.

The atmosphere is opaque to high-energy photons such as X-rays, completely absorbing them, which mandates the use of dedicated space missions for such observations.

Which type of high-energy radiation emitted by celestial objects is completely absorbed by the atmosphere, necessitating space observation?
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