lighthouse1234
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Why is it that I can still use my 10 year old planisphere, if the stars are in motion?
The discussion centers on the apparent motion of stars within constellations, emphasizing that while stars are indeed in motion, their vast distances make their movement imperceptible to the naked eye. The nearest star in Orion, Bellatrix, is 250 light years away, while Alnilam is 1360 light years distant. The visible star with the largest proper motion, 61 Cygni, moves approximately 2.5 arc-seconds over ten years, which is a minuscule change compared to the apparent size of the moon. This phenomenon is likened to observing a train from different distances, illustrating how perspective affects the perception of motion.
PREREQUISITESAstronomy enthusiasts, students studying astrophysics, educators teaching celestial mechanics, and anyone interested in the dynamics of star motion and constellations.
From what moving position?lighthouse1234 said:From that moving position ...
The stars in constellations are so far away that they can be moving tremendously fast and we will not be able to notice it with the naked eye in our lifetime. The nearest star in Orion is Bellatrix, which is 250 light years away. A light year is 5.8 trillion miles. The farthest star in Orian is Alnilim, which is 1360 ly away. So the change in angle will be small unless/until they move very far sideways or up and downlighthouse1234 said:Why is it that I can still use my 10 year old planisphere, if the stars are in motion?
There's a source!lighthouse1234 said:Someone wrote this to me
If I stand far away from the train tracks near my house and watch a train go by, the train appears to move very slowly. If I hold my thumb up it takes about a second for the train to 'cross' behind it. But if I stand next to the tracks the train will cross behind my thumb in a small fraction of a second.lighthouse1234 said:Someone wrote this to me: From that moving position these 'fixed stars' seem to be stationary,
hence are actually moving, even if they seemingly do not.
"There's that guy again, trying to hitch a ride on our train..."Drakkith said:But if I stand next to the tracks the train will cross behind my thumb in a small fraction of a second.