eli5 If we are a spinning ball – spinning in our own solar system – which is spinning within an arm of a galaxy – why are the constellations in the same place?
In: Physics
The distances involved when talking about space are insanely huge. There’s a reason that when we talk about big numbers we call them “astronomical”. Two stars that seem to be inches apart in the night sky are actually billions of miles apart. So if they move another 20 billion miles over a century, they’ll have moved an imperceptible 1/10th of inch by your view.
They are moving though. If you could role the clock back 35,000 years to the time when “we” (as in the first people who genetically resemble modern humans) first appeared, night sky would look quite a bit different.
The simple fact is that space is so vast, that the entirety of written history has happened in the blink of a cosmic eye. We human beings only have a direct account of what the night sky has looked like for a few thousand years, which just isn’t long enough on the a cosmic time line for things to have noticeably change.
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