Megaparsec (Mpc)

AstronomicalCurrent unit

One million parsecs (about 3.26 million light-years). Used for distances between galaxies.

1 megaparsec = 3.085677581×10²² meters (approximately).

About the megaparsec

Galaxies are too far apart for the parsec to be comfortable, so astronomers multiply it by a million. A megaparsec, symbol Mpc, is 1,000,000 parsecs, or roughly 3.26 million light-years and about 3.09 times ten to the twenty-second power meters. It has no article of its own on Wikipedia and is treated as one of the parsec's multiples, alongside the kiloparsec for distances inside a galaxy and the gigaparsec for the largest cosmic structures.

Neighboring galaxies sit at a fraction of a megaparsec: the Andromeda Galaxy is about 0.78 Mpc away, while the Virgo Cluster lies near 16.5 Mpc. Cosmologists also use the unit inside the Hubble constant, quoted in kilometers per second per megaparsec, which expresses how fast distant galaxies recede for each megaparsec of separation. The Milky Way itself is roughly 34 kiloparsecs across, a useful reminder of how much larger intergalactic distances are.

Sources: Wikipedia: Parsec; Wikipedia: Megaparsec (redirects to Parsec)

Megaparsec conversion chart

1 megaparsec expressed in every other length unit:

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