# Calculating the distance of stars

While pondering the other day, I thought about one of the methods they use to measure objects light-years away: Using the Diameter of the earths orbit do measure the parallax of the background stars relative to that which is being observed. Of course this only works so well, considering the tiny distance of our orbit compared to objects hundreds/thousands of LY’s away.

Therefore, would it not make sense to launch a couple of twin space telescopes in opposite directions, get them as far apart as practicality allows, sync them up, then use them to judge distances on a much greater scale?

There already exist much easier ways to find the distance of far away objects. “Easier” meaning less costly, not simpler. http://www.straightdope.com/mailbag/mstardistance.html

Yes, but there’s got to be some other cool advantages to doing this. Stereoscopic Vision on a macro scale for one?

The OP is a good idea. The problem with those non-parallax methods is that they depend on the parallax. Well, the parallaxen (like all measurements) are not precise and, even for nearby stars, there is some uncertainty in the results. But measuring standard candles (as discussed by Chronos) is also not precise. So you end up with two measurements contributing their errors in the standard candle methods.

So getting a bigger baseline will let us measure parallaxen more accurately and for objects further away. So it will make the standard candle measurements more accurate.

We’ve already gotten much improvement in parallax measurements with the Hipparchos satellite. It was just in Earth orbit so it had the same baseline as on Earth, but it was above the atmosphere, which reduced the errors significantly. Unfortunately, it had a lower limit on the brightness of the objects that it could see. So it didn’t measure the distance to faint stars, including some that are within a few parsecs of Earth.