Parsecs to Inches (pc to in)

1 parsec equals 1.214833694×10¹⁸ inches (rounded).

1 parsec = 1.214833694×10¹⁸ inches

How to convert parsecs to inches

To convert parsecs to inches, multiply the number of parsecs by 1.214833694×10¹⁸. The factor is rounded to 10 significant digits. To go the other way, multiply inches by 8.231579395×10⁻¹⁹ (rounded).

inches = parsecs × 1.214833694×10¹⁸

Example: 10 parsecs = 1.214833694×10¹⁹ inches.

About these units

Parsec (pc)

AstronomicalCurrent unit

About 3.26 light-years, defined as 648,000/π astronomical units. The standard unit for distances to stars.

British astronomer Herbert Hall Turner coined the word in 1913 as a contraction of the distance at which a parallax equals one arcsecond. Rivals were Frank Dyson's astron and Carl Charlier's siriometer. The idea rests on stellar parallax, first measured successfully by Friedrich Bessel in 1838 for 61 Cygni, which he put near 3.5 parsecs. With the angle in arcseconds, the distance in parsecs is simply its reciprocal.

Since 2015 the IAU has defined the parsec as exactly 648,000 divided by pi astronomical units, which with the 2012 exact au gives about 30,856,775,814,913,673 meters, or 3.0857 times ten to the sixteenth power. That is roughly 3.26 light-years. Proxima Centauri lies about 1.3 parsecs away. Professional astronomers still prefer the parsec to the light-year, and ESA's Gaia satellite, launched in 2013, measures parallaxes to microarcsecond precision.

1 parsec = 3.085677581×10¹⁶ meters (approximately).

Sources: Wikipedia: Parsec; NIST SP 811 Appendix B.8: factors for units outside the SI

Inch (in)

US & ImperialCurrent unit

1/12 of a foot. Defined as exactly 25.4 millimeters since 1959, when the US and Commonwealth countries agreed a common international inch.

Latin uncia, meaning one-twelfth, is the root of both inch and ounce, and it passed into Old English as ynce. Roman measurers divided their foot into twelve unciae, and the English inch kept that twelfth. After 1066 an inch was reckoned as three barleycorns, and a 1324 statute attributed to Edward II spelled out the definition as three grains of barley, dry and round, placed end to end lengthwise. For centuries the inch was simply a twelfth of a foot, or a thirty-sixth of a yard, and the US and UK each kept their own copy of the standard yard.

Those copies differed slightly until the 1959 international agreement fixed the yard at exactly 0.9144 meter, which made the inch exactly 25.4 millimeters. The US adopted it in 1959 and the UK ratified it in 1963, effective 1964. Today the inch is still the customary unit in the United States and Canada, and the UK keeps it on road signs. Worldwide it also names display diagonals, wheel rims, tire codes and pipe sizes.

1 inch = 0.0254 meters (exactly).

Sources: Wikipedia: Inch; Wikipedia: Yard; NIST Guide to the SI, Appendix B.8: conversion factors

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