What are the advantages of using the Parsec over the lightyear?

Question

Lydia Allen · Accepted Answer

If two equidistant light sources 1 AU apart reveal angular spacing of #1"= 1/3600^o#, the common distance is 1 parsec. If this angle is 100", quite easily, the distance is 100 parsecs. .

While parsec is a distance unit with additional benefits, light year is a unit of distance focused on light speed. When examining the dimensions of galaxy clusters located thousands or millions of light years away, the parsec measure proves to be highly valuable. One astronomical unit (AU) is equal to 149597871 kilometers. The parsec calculation formula is the length of circular arc subtending #theta# at the center of a circle of radius R, L = R#theta#. Here, L is in R units. One parsec is equal to 1/(1" radian, the angular spacing) AU. Thus, 1 parsec #=(1/3600)(pi/180)# AU = 206264.8 AU When the angular spacing is relatively small, it should be noted that the linear spacing between extremely far apart equidistant objects is roughly equal to the circular arc length.

Hunter Arthur · Answer

undefined The advantage of using parsec over lightyear is that parsec is a unit of distance commonly used in astronomy, specifically for measuring large distances between celestial objects within the Milky Way galaxy, while lightyear is a unit of distance used to measure vast distances across the universe. The advantage of parsec lies in its convenience for measuring distances within our galaxy, as it is based on the parallax effect and is directly related to the astronomical unit, making it useful for nearby celestial objects.