Kiloparsec

Kiloparsec (kpc) is a unit of length used in astronomy to express distances on galactic scales. It equals 1000 parsecs, where a parsec is defined as the distance at which 1 astronomical unit subtends an angle of one arcsecond. A parsec is about 3.0857×10^16 meters, and roughly 3.26 light-years, so 1 kiloparsec is about 3.0857×10^19 meters, or about 3,262 light-years.

Kiloparsec is commonly used to describe distances within the Milky Way and the sizes of nearby galaxies. For example, the Sun is located at about 8 kpc from the Galactic Center. Disk radii, spiral-arm separations, and stellar halo extents are often expressed in kpc. For more distant galaxies, astronomers generally use megaparsecs, where 1 Mpc equals 1000 kpc.

The kiloparsec is part of the parsec family of units, rooted in the method of measuring stellar distances through parallax. It provides a convenient, manageable scale for describing the structure and extent of the Milky Way and neighboring galaxies without resorting to very large numbers in parsecs or meters.