I'm curious about stars and I am wondering why a star would change its position in the sky due to another star right next to it?

  • $\begingroup$ "due to" - do you mean that another star is influencing it? $\endgroup$ – HDE 226868 Feb 21 '15 at 22:54
  • $\begingroup$ Yes that is what i meant to say $\endgroup$ – Username123 Feb 21 '15 at 22:56
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    $\begingroup$ Still not clear what you mean. Do you mean the relative positions of two stars you can actually see in the sky? Or do you mean a pair of stars that can be separated with a telescope? $\endgroup$ – ProfRob Feb 22 '15 at 0:50
  • $\begingroup$ Is this something you've actually observed? If so, please update your question with the details. $\endgroup$ – Keith Thompson Feb 24 '15 at 18:18
  • $\begingroup$ Are you sure you're not looking at a planet? $\endgroup$ – user21 Feb 26 '15 at 13:49

The answer is gravity.

Stars have a lot of mass so there for there gravity is strong.

If 1 star gets close to another star that has slightly more mass this would mean that it gets pulled in. As a result the orbit would change.


This does not affect all stars due to the distance they are from each other. Usually if it affects start it is in binary systems.

Thanks to Joan.bdm for this.

  • $\begingroup$ I don't really think Username123 talks about binary systems. He/She is probably refering to stars that "seem to be close to each other" from our point of view but they are so far that gravity effect between them is negible. $\endgroup$ – Joan.bdm Feb 23 '15 at 7:21
  • $\begingroup$ I thought gravity would have affected it anyway. It is the gravity from the sun which keeps all our planets in orbit. $\endgroup$ – iProgram Feb 23 '15 at 7:38
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    $\begingroup$ Yes, you are right. Gravity between stars affect their motion, but most of the stars we see in the sky although they seem to be so close from our point of view they are too far to be affected from one to the other. But you are right, some of them, the closest ones, are affected by gravity. For example in some binary systems you'll see 1 or 2 stars depending on their relative position. Actually all stars are in motion, but they are so far this movement is only visible in long terms. $\endgroup$ – Joan.bdm Feb 23 '15 at 8:45
  • $\begingroup$ Thanks for that information. I have edited my answer. Could you make sure that I got what you meant please? $\endgroup$ – iProgram Feb 24 '15 at 17:43

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