Parsec
The parsec is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (au), i.e., 30.9 trillion kilometres. The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond. The nearest star, Proxima Centauri, is about 1.3 parsecs from the Sun: from that distance, the gap between the Earth and the Sun spans slightly less than one arcsecond. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand parsecs, and the Andromeda Galaxy at over 700,000 parsecs (2,283,000 ly).
On WikiTrade, every Wikipedia article is a card: the more the article is read, the rarer the card. Open free packs, complete your album, trade, bid and challenge others to general-knowledge duels.
Play for freeRead the article on WikipediaText from Wikipedia (CC BY-SA 4.0). WikiTrade is an independent site, not affiliated with Wikipedia or the Wikimedia Foundation.