The parsec is a unit of measure used in astronomy it is equal to 3.26 light years and it was introduced in 1913 by the Yorkshire astronomer H.H. Turner 1861-1930. He said that a star at a distance of 1 parsec would have a parallax of 1 second of arc. A parallax is the movement of a star against a starry background.
The best way to show what is meant is to make a practical experiment, Shut one eye, and line up your finger with an object some way away such as a bush or tree in your garden. Now without moving your finger or head, open that eye and use the other one. Your finger will no longer be aligned with that bush or tree. If you know the distance between your eyes and the angular shift of your finger against the background , it is possible using a little bit of trigonometry to work out the distance between your finger and your eyes.
Herbert Hall Turner was born in Leeds and educated at Leeds Modern School , he went onto study at Trinity College, Cambridge. Turner become chef assistant at the Royal Greenwich Observatory before becoming Savalian Professor of Astronomy at Oxford and then director at the Radcliffe observatory. He was at Southport in Lancashire to observe the 1927 eclipse of the Sun.
In 1930 Pluto was discovered and it was named by a 10 year girl from England called Venetia Burney. Her grandfather Falconer Madan was librarian at the Bodleian Library at Oxford who knew Turner, who in turn knew astronomers at the Lowell observatory where Pluto had been discovered. He telegraphed the suggestion to them where the name of Pluto was adopted.
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