Just learned why Andromeda looks so big in photos even though it's 2.5 million light years away

I read on NASA's site that the galaxy's actual disk is over 200,000 light years across, way bigger than the Milky Way. Did anyone else not realize how massive it really is until they saw those comparison shots?

2 comments

2 Comments

drewgonzalez11d ago

Gotta disagree with you a bit on this one. Yeah it's huge, but the brightness tricks us more than the size does. Andromeda is actually pretty faint in the sky, you can barely see it with your naked eye even though it's that big. Those photos are just long exposure shots that make it pop way more than it really does. Size matters but light pollution and exposure time play a bigger role in those dramatic pictures than the actual dimensions.

jasonf179d ago

But how does that square with the fact that its angular size in the sky is actually six times wider than the full moon? I get that faintness matters, but if it covers that much area, the raw physical scale is still pretty wild even without the long exposure. Is the average person just not looking for it in the right conditions, or does our eye really miss that much?

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