How Do Scientists Estimate the Distance to Stars?

[zli034]

Think about this, a photon travel through the universe, its path can be reflected by other objects, bended by gravity. Therefore the path would not be a straight line anymore. But very often from the TV science shows stating the distances to other stars are some some million light years.

How did they get the distance in light years? Are we able to measure the distance to the stars?

 

[NobodySpecial]

For pretty much all the stars we see the light came more or less straight to us.

The distance to stars is a fascinating subject.

The nearest stars we can measure the distance to directly by something called parallax.
Hold out you finger and close each eye in turn, you see the finger move compared to distance obejcts. Now if you know the distance between your eyes and the angle the finger seemed to move against the background you can measure the length of your arm.
If you measure the position of a star (very accurately) 6months apart - so the Earth has moved from one side of the sun to the other. then you can measure the distance to the nearest 10,000 or so stars very accurately.

Beyond that it gets a bit less exact. We might see a nearby star that we know the distance to and be able to measure it's temperature and chemistry, we then see a fainter star with the same signature we can guess that it's the same absolute brightness and so from how much fainter it seems to us we can estimate how much further away it must be

 

[mathman]

Try google "measure distance to stars". It is complicated in that nearby stars are measured by parrallax while further away stars and galaxies use various other measures depending on distance.

 

[Kracatoan]

http://en.wikipedia.org/wiki/Cosmic_distance_ladder might be of use.