How do we really know how far away stars are?

I have read a couple of books on science so now I'm dangerous. Einstein tells us that gravity bends light and as a result light follows a curved path. I've also read that spacetime is curved.If that is the case how can we really know what the actual distances to the various stars are and how do we actually know how many there are?Using our planet for example. I am standing on the North Pole. I have an omni directional radio antennae and I send off a signal. My buddy is down at the South Pole. He has a direction finder on his receiver and he also knows to the nanosecond the time the signal was sent.With his direction finder he finds that he is receiving the signal from a number of different directions, (even though they are all North ), as no matter along which line of longitude the signal travels it is the same distance.By knowing the exact time it took the signal to travel that distance he can now calculate the distance to the North Pole.Let's review the findings. What is the direction to the North Pole? The signal was omni directional so we actually received many different signals at the South Pole even though they all originated from the same place.The distance that we have measured only gives us the distance that the signal travelled on its curved track around the circumference of the planet. In actuality there was a much shorter route right through the center of the Earth. In other words we measured an arc in instead of the direct route.Stay with me here. I'm doing the best I can. Honest.Now then let's apply this to a star. If light curves as it is pulled by gravitational forces how do we know that what we are measuring is really a straight line. Maybe for instance if light were to travel in a straight line the star we are now seeing in Canada would instead be seen from Australia.Also of course because light is travelling in an arc the direct distance to the star might be considerably closer than what we measure.My last point is that because light is emitted omni directionally who is to say that we are not seeing the same star in a number of different locations depending upon the route that the light took to get here.Man I hope that all makes sense. This message has been edited by GDR, 06-17-2005 08:55 PM

Thread copied to the How do we really know how far away stars are? thread in the Big Bang and Cosmology forum, this copy of the thread has been closed.