Micrometers to Light-years (µm to ly)

1 micrometer equals 1.057000834×10⁻²² light-years (rounded).

1 micrometer = 1.057000834×10⁻²² light-years

How to convert micrometers to light-years

To convert micrometers to light-years, multiply the number of micrometers by 1.057000834×10⁻²². The factor is rounded to 10 significant digits. To go the other way, multiply light-years by 9.460730473×10²¹ (rounded).

light-years = micrometers × 1.057000834×10⁻²²

Example: 10 micrometers = 1.057000834×10⁻²¹ light-years.

About these units

Micrometer (µm)

Metric (SI)Current unit

One millionth of a meter, also called a micron. Typical bacteria are a few micrometers long; a human hair is roughly 70 µm thick.

Two names, micron and micrometer, have shared this unit for more than a century. The prefix micro- was adopted in 1873 alongside the CGS system, and in 1879 the term micron and the symbol μ were officially accepted for the micrometer when used on its own. That created a clash once SI came along: μ was also the symbol for the prefix micro-. The 13th CGPM revoked micron and its symbol in 1967 to 1968, leaving micrometer and μm as the official name and symbol, though micron lives on in everyday speech.

A micrometer is a thousandth of a millimeter, and it is the natural scale for biology and filtration. A typical red blood cell is 6 to 8 μm across, a bacterium is 1 to 10 μm long, and a fog droplet is around 10 μm. Human hair ranges from about 17 to 181 μm in diameter, and paper is 70 to 180 μm thick. Infrared radiation is measured in micrometers of wavelength, and wool is graded by fibre width. Some American writers keep micron because micrometer also names the caliper-style measuring tool.

1 micrometer = 0.000001 meters (exactly).

Sources: Wikipedia: Micrometre; Wikipedia: Metric prefix

Light-year (ly)

AstronomicalCurrent unit

The distance light travels in one Julian year: exactly 9,460,730,472,580,800 meters (about 9.46 trillion km).

Despite the name, a light-year measures distance rather than time, and its coinage is a little later than most people assume. Friedrich Bessel measured the distance to the star 61 Cygni in 1838 but did not use the unit himself. The light-year appeared in print in 1851, in a German article by Otto Ule, who explained its odd use of a time word by comparing it to saying that a place is an hour's walk away.

The International Astronomical Union defines it as the distance light travels in a vacuum in one Julian year of 365.25 days, about 9.46 trillion kilometers. NIST lists it as 9.460 73 times 10 to the 15th meters. Light-years dominate popular science, while professional astronomers mostly prefer the parsec, about 3.26 light-years. For scale, Proxima Centauri, the nearest star to the Sun, is about 4.24 light-years away, and the Milky Way is roughly 100,000 light-years across.

1 light-year = 9.460730473×10¹⁵ meters (approximately).

Sources: Wikipedia: Light-year; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

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