The European Space agencies mission Gaia is an ambitious mission to chart the st

Question

The European Space agencies mission Gaia is an ambitious mission to chart the structure of our Galaxy. It will produce positional measurements of 1 billion stars! The accuracy of these measurements will be on the order of 25 micro-arcseconds.

a) To get an idea of the quality of this resolution, how far would a quarter have to be to subtend this same angle? Assume that a quarter is 25mm in diameter.

b) Assuming a distant star produces a parallax equivalent to the resolution of Gaia, what is the maximum distance that Gaia can accurately determine the distance of stars?

c) Would this distance found in (b) allow us to map all the visible stars in our Galaxy?

d) Will it allow us to measure parallaxes to any nearby galaxies? If so give their names.

Explanation / Answer

a) far would a quarter have to be =   2 * 3.14 * 0.0125/4

                                                     = 0.0196 m

b) maximum distance that Gaia can accurately determine = 3 * 108 * 0.0196

                                                                                            = 5.88 * 106 m

c) Yes, this will allow us to map all the visible stars in our Galaxy .

d) No, it will not allow us to measure parallaxes to any nearby galaxies .

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