Question

The GAIA spacecraft is capable of measuring parallax angles as small as about 0.00002 arcseconds (20 microarcseconds). Based on this fact, GAIA should in principle be able to measure the distances of stars located __________.

Answer 1

It will be able to measure the distances of stars located across the Milky Way galaxy and outside it up to a distance of 50 Kiloparsec.

Step-by-step explanation:

1 arcsecond is 1/parsec.

0.00002 arcsecond is 1/0.00002 parsec = 50,000 parsecs or 50 Kiloparsecs.

The shortest distance to the edge of the Milky Way is about 8 Kiloparsec and the farthest is about 24 Kiloparsec. So at this parallax angle, it can measure the distances of stars across the Milky Way galaxy. Any stars within a distance of 50 Kpc will be measured by GAIA. However, since the closest galaxy to the Milky Way is about 770 Kpc away, GAIA will be unable to measure any stars in another galaxy.