parsec

Everyday

(science) A unit for measuring huge distances in space, equal to about 3.26 light years, or about 31 million million kilometres. tree →

In the lessons

In space and science lessons, astronomers use parsecs and light years because kilometres are far too small. The nearest star to the Sun, Proxima Centauri, is about 1.3 parsecs away. Fans of Star Wars know the line about the Kessel Run «in less than twelve parsecs».

Examples

• A parsec is about 3.26 light years. tree →
• The nearest star is a little over one parsec away. tree →
• Astronomers measure the distance to galaxies in millions of parsecs. tree →
• In Star Wars, Han Solo boasts about doing the Kessel Run in twelve parsecs. tree →
• A parsec is a measure of distance, not time. tree →
• The galaxy is about 30,000 parsecs across. tree →

Note

Countable. A common trap (even in films): a parsec measures distance, not time. Maths: 1 parsec ≈ 3.26 light years ≈ 31 trillion km (31,000,000,000,000 km); a kiloparsec = 1,000 parsecs, a megaparsec = 1,000,000 parsecs. The name comes from «parallax second».