Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Speed & Path of Galaxy

  1. Jul 23, 2010 #1
    We all know that Galaxies are moving away from each other at a great speed, Is there any specific path through which they are moving?

    Again we know few things about the Universe like Moons rotate around Planets, Planets around star, stars around the center of galaxy. And it seems all follow a system & that is the Gravitational force.

    Earlier astronomers felt like earth is constant & Sun is moving around it, but gradually they came to know the actual fact. Till now we know about the Stars as they rotate around the center of galaxy i.e. the black hole, So it may happen black holes are also rotating around some massive force along with the Galaxy. If that is true then all Galaxies are having a path & it will reject the concept that Universe is Expanding.

    Here One more thing is that the distance between two planets in our Solar system never be same always, sometimes we may see the distance is getting more & sometimes less. This all because of the paths & we know this, as these planets are much close to us as compared to distant galaxies.

    I feel we can find out this once we have some more powerful Telescope that we have now.

    Whatever the astronomers found till date about the Universe is nothing but an Organized System, every object is well placed with a specific path, whereas the fact that Galaxies are moving away from each other is not matching the whole concept that already proved by astronomers.
     
  2. jcsd
  3. Jul 23, 2010 #2

    russ_watters

    User Avatar

    Staff: Mentor

    Except for ones near enough to each other to be gravitationally bound, they are all moving directly away from each other at a speed roughly proportional to their distance from each other (ie, the further apart, the higher the speed).
    Motion of galaxies can be easily measured via red-shift, so astronomers are pretty sure they know the recession velocity of the galaxies reasonably accurately.
    Again, we can certainly tell whether galaxies are getting closer to us or moving away.
    Astronomers will always want more powerful telescopes, but as far as confirming the Big Bang theory goes, the margin for error is already exceedingly small. The Hubble can already see and measure the speed of objects more than 13.2 billion light years away - just a few hundred million years after the Big Bang and not long after galaxies started to form.
    I'm not quite following: there are no big flaws in the BBT. The fact that galaxies are moving away from each other matches with the predictions of the BBT.
     
  4. Jul 23, 2010 #3
    Thanks for your great explanation, I have one more question "What is the major factor behind the speed of any object in space?". The speed of a star, planet, moon all varies. E.g. If a planet is close to the star then it will be be having greater speed than the planet that is far away. Similarly Speed of the Galaxies are also vary to each other, What is the factor behind this?
     
  5. Jul 23, 2010 #4

    russ_watters

    User Avatar

    Staff: Mentor

    Objects that are close enough to each other to be gravitationally bound are interacting due to gravity. That would be the planets, stars, etc. up through our local group of galaxies. All of this motion one way or another started as gravitational potential energy as the slight granularity of our early ball-of-plasma universe led to coalescing into these forms.
    Beyond our local group of galaxies, the word "motion" as we normally think about it is not really applicable any more. Objects appear to be moving apart, but the reality is that the space between them is expanding. Though the word is often still used, it isn't the same kind of motion.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook