Megaparsecs to Millimeters (Mpc to mm)

1 megaparsec equals 3.085677581×10²⁵ millimeters (rounded).

1 megaparsec = 3.085677581×10²⁵ millimeters

How to convert megaparsecs to millimeters

To convert megaparsecs to millimeters, multiply the number of megaparsecs by 3.085677581×10²⁵. The factor is rounded to 10 significant digits. To go the other way, multiply millimeters by 3.240779289×10⁻²⁶ (rounded).

millimeters = megaparsecs × 3.085677581×10²⁵

Example: 10 megaparsecs = 3.085677581×10²⁶ millimeters.

About these units

Megaparsec (Mpc)

AstronomicalCurrent unit

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

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.

1 megaparsec = 3.085677581×10²² meters (approximately).

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

Millimeter (mm)

Metric (SI)Current unit

One thousandth of a meter. Used in engineering, manufacturing and rainfall measurement.

Carl Friedrich Gauss put the millimeter at the base of his 1832 proposal for absolute units, pairing it with the milligram and the second, although the centimeter-based CGS system later won out among scientists. The name combines the metric prefix milli-, from the Latin for one thousand, with the meter. Since 1983 a millimeter has been tied to the speed of light: it is the distance light covers in 1/299,792,458,000 of a second.

Millimeters are the language of fine mechanical work. Standard rulers are divided into them, digital calipers commonly read to 0.01 mm, and mechanical pencil leads come in 0.5 and 0.7 mm. Copy paper is about 0.1 mm thick, and a thin hair, at 0.02 to 0.04 mm across, is close to the smallest thing the naked eye can see. A wave with a frequency of 300 GHz has a wavelength of 1 mm. An inch is exactly 25.4 mm. One trap for readers in the United States is that mil there traditionally means a thousandth of an inch, not a millimeter.

1 millimeter = 0.001 meters (exactly).

Sources: Wikipedia: Millimetre; Wikipedia: Centimetre-gram-second system of units; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

See all length units.