How do stars manage to create the same constellations multiple times?



I don’t see a flair option for Astronomy…

But I just recently wondered how stars could line up perfectly to create an Orions belt or many other shapes. Not only that but how do constellations end up being formed more than once? Are we looking at the same stars?

In: Physics

They’re all really far away and so they stay in about the same location from us all the time. The only reason they moved through this sky is because of how the Earth spins and tilts and rotates around the sun.

So the stars for every culture is the same if the are on the same angle of the planet (0 at the equator and + or – 90 at the poles). These stars don’t line up to paint pictures though. More that there are a few bright ones and people imagine shapes around them. For example if I put three dots on a page (with size according to how bright the star is) as stars appear in the night sky you may see completely different patterns or none at all. Orion’s Belt specifically is just three stars in the sky. They look nothing like a belt but some guy long ago made up some wak ass story about a warrior fighting a bull.

Stars are just randomly placed in the sky. There is objectively no patterns to them and they do not form constillations. In fact because space is three dimensional the stars which might look close from our vantage point may be hundreds of light years apart. We only see constillations because we are looking for patterns. And we are so good at looking for patterns that we find patterns in any random scattered points in the sky. But if you look at different cultures you will notice that they have found different patterns and therefore have different constillations.

To add to the other comments, most stars that make up constellations aren’t in a straight line in 3D space. They’re all at varying distances from the Earth, and only appear 1) to be similarly bright because the farther stars are brighter, and 2) to be in a straight line because of the specific point of view that we have from Earth. From a different vantage point surrounding a different star, the three stars in Orion’s belt may not all appear in the same region of sky at all.

The stars in Orion’s belt are always the same stars, The only objects that move around enough to notice without careful long term records or telescopes are the ones in our own solar system. What’s moving is you, and the planet. It’s like putting a photo on your wall, then slowly spinning your chair so you end up facing the same direction a day later. The photo is still the same, you’re just facing the right way to see it again.

There’s open source software called Stellarium, you can turn off the atmosphere and ground, to see where the stars are when it’s daytime, or put in a location to see what stars are visible from where at any given time. You can also fast forward time, it’s definitely worth playing around with. Sometime I’ll notice a star or planet, try to work out which one it is, then check stellarium to see if I was right.