We are about 8000 parsecs from the center of the Milky Way Galaxy,and the smallest parallax angle we can measure from orbiting observatories is about 0.001 arcseconds.How far toward the galactic center can we see with this technique (ignoring galactic dust and other obstacles)?
A) all the way to the center
B) about halfway to the center
C) about 1/8 of the way to the center
D) only 0.008 = 1/125 of the way to the center

Question

Quizplus · Accepted Answer

Using trigonometry, we can calculate the distance we can see toward the galactic center using the parallax angle:
tan(theta) = (distance from Earth to center of the galaxy) / (8000 parsecs)
Rearranging the equation:
distance from Earth to center of the galaxy = tan(theta) x 8000 parsecs

With a parallax angle of 0.001 arcseconds, we get:
distance from Earth to center of the galaxy = tan(0.001 arcseconds) x 8000 parsecs = 0.008 x 8000 parsecs = 64 parsecs

So, we can see about 1/8 of the way toward the galactic center with this technique, hence the correct choice is C.

We Are About 8000 Parsecs from the Center of the Milky