Heard a kid at the observatory ask why stars twinkle but planets don't

Stood next to this dad and his son during a public viewing night at the local astronomy club meetup. The volunteer explained it's all about atmospheric turbulence and the size of the light source. Stars are point sources so the air bends them around, planets have a visible disk so the effect averages out. Never really thought about it that way before. Anybody else have that moment where a simple question made you realize you took something for granted?

2 comments

2 Comments

james_torres17d ago

That bit about the light source size really clicked for me too (it's one of those things you never question until a kid pipes up). If you're ever explaining it to someone, grab a flashlight and a laser pointer - shine them through a ripply glass of water to show how the steady blob vs the dancing dot works. It's a super hands-on way to make the point stick without getting all technical.

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oliviahenderson17d ago

Friend of mine tried that with a laser pointer and accidentally shined it in his own eye, oops.