Calculate the ratio of the distance from earth to the most d

Calculate the ratio of the distance from earth to the most distant stars for which parallax is measureable to the distance from earth to the center of the Milky Way.

Solution

Smallest measurable parallax, 0.01 arcsec. This means largest distance that can be seen d = 1/0.01 = 100 pc.

Distance of earth from center of galaxy D=30 kpc. Hence d/D = 100/30000 = 1/300 = 0.0033