What is 1 parsec?
“The parsec (“parallax of one arcsecond”, symbol pc) is a unit of length, equal to just under 31 trillion kilometres (about 19 trillion miles), or about 3.26 light-years. The parsec is used in astronomy. The parsec is defined as the length of the adjacent side of an imaginary right triangle in space. The two dimensions that form this triangle are the parallax angle (defined as 1 arcsecond) and the opposite side (which is defined as 1 astronomical unit (AU), the distance from the Earth to the Sun). Given these two measurements, along with the rules of trigonometry, the length of the adjacent side (the parsec) can be found. One of the oldest methods for astronomers to calculate the distance to a particular star was to record the difference in angle between two measurements of the position of the star in the sky. The first measurement was taken from the Earth on one side of the Sun, and the second was taken half a year later when the Earth was on the opposite side of the Sun. Thus, the di
