|MadSci Network: Astronomy|
Yes, we could in principle get more precise parallaxes by putting a satellite in an orbit which has a larger baseline.
For example, if you placed a satellite in an orbit like that of Jupiter, the parallaxes would be about 5 times more accurate than from the Earth. The one disadvantage is that a satellite in a large orbit moves slowly. Jupiter, as you probably know, orbits the Sun about every 12 years, so it would take a long time to gather the data!
In fact, satellites have been used to measure extremely accurate parallaxes. The Hipparcos Space Astrometry Mission measured extremely accurate distances to many thousand stars. It achieved its high accuracy not because it had a large baseline (it merely was in orbit about the Earth, so the baseline was the same) but because images taken in space are free of the atmospheric blurring that happens with telescopes on the ground. Blurred images will yield lower accuracy than sharp ones.
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