The Big Bang scattered planets and stars everywhere in three dimensions.

But after billion years of moving and interacting with each others through gravity, planets moved on the same plane.

Given the very small but non zero friction in space, could we give a good estimate of the age of the universe?

  • 4
    $\begingroup$ Simple answer - no: The planar geometry of the solar system is totally unrelated to the age of the universe. $\endgroup$
    – ProfRob
    Sep 13, 2015 at 21:32
  • 2
    $\begingroup$ The Solar system formed well after the BB, but, of course, its age (which we can meaure from isotope ratios) is a lower limit for the age of the universe, though not a very useful one. $\endgroup$
    – Walter
    Sep 14, 2015 at 9:05
  • $\begingroup$ Why the negative votes ? The question is so dumb ?? $\endgroup$
    – Thomas
    Sep 19, 2015 at 2:41

2 Answers 2


First, the Big Bang did not happen at a point. I cannot emphasize this enough. It happened everywhere in space at the same time. You can't think of it as an explosion from one location pushing everything else away.

Furthermore, planets and stars didn't exist at the time of the Big Bang. The Solar System, for example, formed about 4.5 billion years ago, while the oldest stars - Population III stars - formed within a few million years after the Big Bang. At the beginning of the universe, everything was in an exotic soup-like state: a quark-gluon plasma.

Therefore, your hypothesis is flawed in two places.

  • $\begingroup$ ok, it is an image, but still, does it make sense ? $\endgroup$
    – Thomas
    Sep 13, 2015 at 20:12
  • $\begingroup$ @Thomas No, because it happened everywhere. $\endgroup$
    – HDE 226868
    Sep 13, 2015 at 20:13
  • $\begingroup$ @HDE_226868 ok, I didn't know that, but still my question holds : stars and planets formed in a 3D manner, not in a plane. why are they in a plane now ? because of gravity and friction and time. no ? $\endgroup$
    – Thomas
    Sep 14, 2015 at 18:19
  • $\begingroup$ @Thomas See astronomy.stackexchange.com/questions/130/… and astronomy.stackexchange.com/questions/2224/…. The same logic holds (to some extent) on a galactic scale. $\endgroup$
    – HDE 226868
    Sep 14, 2015 at 19:05
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    $\begingroup$ @Thomas The protoplanetary disk. $\endgroup$
    – HDE 226868
    Sep 19, 2015 at 20:58

No, the formation of planetary systems is not the result of the interaction of stars and planets which form at random in space post Big Bang. Stars form from density fluctuations in the gas in galaxies and planetary systems usually form (to the best of our knowledge) from the disks of gas and dust around stars that are a side effect of the formation of stars.

That is planar planetary systems should be usual because they form from planar systems which are largely the result of dynamical processes in star formation.


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