eli5: if everything in the universe is constantly revolving at insane speeds, why are the constellations and star patterns the same all the time?
In: Physics
The objects in the universe are not all revolving around some central point in the universe, Earth or otherwise. They are rotating around their own axes and revolving around the centers of mass of their immediate systems, such as planets revolving around parent stars or stars revolving around the center of their galaxies. In the case of the stars that we can see, they are all revolving around the gravitational center of our own Milky Way galaxy.
Still, star patterns/constellations are NOT always the same. They are constantly changing as the Earth and these stars move relative to each other while revolving around the center of our galaxy. However, these changes are too small for us, observing the night sky with only our eyes, to notice on the scale of human lives. This is because of how far away they are: there is a reason we call very long measurements “astronomical”. In tens of thousands of years and longer, constellations will appear different to how they appear now. They appeared different thousands of years ago too. We’ve only had the means to precisely catalogue and capture star positions for a very short time, though.
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