Parsec (redirected from Megaparsecs)

parsec (pär`sĕc) [parallax + second], in astronomy, basic unit of length for measuring interstellar and intergalactic distances, equal to 206,265 times the distance from the earth to the sun, 3.26 light-years, or 3.08 × 10¹³ km (about 19 million million mi). The distance in parsecs of an object from the earth is the reciprocal of the parallax of the object. The nearest star, Proxima Centauri, has a parallax of 0.763" of arc and a distance of about 1.31 parsecs.

---

parsec

Unit of measure used by astronomers to express distances to stars and galaxies. It is the distance at which the radius of Earth's orbit would subtend an angle of one second of arc, so an object one parsec away would have a parallax of one second. An object's distance in parsecs is the reciprocal of its parallax in seconds of arc. For example, Alpha Centauri, with a parallax of 0.76 second, is 1.33 parsecs from the Sun and Earth. One parsec equals 3.26 light-years, or 19.2 trillion mi (30.9 trillion km).

---

parsec

a unit of astronomical distance equal to the distance from earth at which stellar parallax would be 1 second of arc; equivalent to 3.0857 × 10¹⁶ m or 3.262 light years

---

parsec [′pär‚sek]

(astronomy)

The distance at which a star would have a parallax equal to 1 second of arc; 1 parsec equals 3.258 light-years or 3.08572 × 10¹³kilometers. Derived from parallax-second.

---

PARSEC - Extensible language with PL/I-like syntax, derived from PROTEUS. "PARSEC User's Manual", Bolt Beranek & Newman (Dec 1972).

---

Parsec 

a unit of distance in astronomy equal to 206,265 astronomical units, or 30,857 X 10¹² km; its international abbreviation is pc. Distance expressed in parsecs is the reciprocal of the annual parallax. Thus, a distance of 10 pc corresponds to a parallax of 0.1”. In fact, the name “parsec” derives from these last two values—”parallax of one second.” One parsec is equal to 3.26 light-years.