Parsec Parsec The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System. A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond, which corresponds to astronomical units. One parsec is equal to about 3.26 light-years (30 trillion km or 19 trillion miles) in length. The nearest star, Proxima Centauri, is about from the Sun. Most of the stars visible to the unaided eye in the night sky are within 500 parsecs of the Sun. The parsec unit was probably first suggested in
USS PC-823 York, ROKN’s first ocean-going naval vessel, Baek-du-san (PC-701) was born. Sailing from New York, a 3-inch main deck gun was attached at the Hawaii Naval Station, and 100 shells were purchased at Guam. PC-701 finally arrived at Jinhae Naval Base, South Korea, on 10 April 1950, barely two months before the June 1950 outbreak of the Korean War. With only 100 rounds ammunition, the sailors could only practice aiming the main gun, not firing it. On the night of 25/26 June 1950, on the South Korean eastern coast, she patrolled against infiltrators from the north. About twenty miles from the