ELI5: the forbidden atmosphere

// eli5

What is a forbidden atmosphere?

"Forbidden" in astronomy refers to special light patterns that scientists thought were impossible to see in space [2]. When atoms like oxygen get excited in a planet's atmosphere, they can release light in unusual ways that were predicted to be "forbidden" by old physics rules [2].

Why is it called forbidden?

Scientists used to think certain atoms couldn't emit light in particular ways because the physics rules said no [2]. It's like a rule that says "you can't do this" — but nature sometimes breaks the rule anyway [2].

What does forbidden light look like?

When forbidden emissions happen, atoms release a special green or red glow that's different from normal light [2]. Think of it like a traffic light that shouldn't be able to glow, but somehow does anyway [2].

Why do scientists care?

Finding forbidden emissions helps scientists understand what's happening high up in a planet's atmosphere [2]. It's like a secret message that tells us about the temperature and chemicals floating around up there [2].