Light-years to Meters (ly to m)
1 light-year equals 9.460730473×10¹⁵ meters (rounded).
How to convert light-years to meters
To convert light-years to meters, multiply the number of light-years by 9.460730473×10¹⁵. The factor is rounded to 10 significant digits. To go the other way, multiply meters by 1.057000834×10⁻¹⁶ (rounded).
meters = light-years × 9.460730473×10¹⁵
Example: 10 light-years = 9.460730473×10¹⁶ meters.
About these units
Light-year (ly)
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
Meter (m)
The SI base unit of length. Since 1983 it is defined as the distance light travels in a vacuum in 1/299,792,458 of a second.
Meter comes from the Greek metron, a measure. In 1791 the French National Assembly defined it as one ten-millionth of the distance from the equator to the North Pole along a great circle through Paris, after rejecting the length of a seconds pendulum because that length changes with local gravity. The surveyors Delambre and Méchain measured the meridian arc, and in 1799 a platinum bar known as the Mètre des Archives became the physical standard. NIST notes that this Earth-based meter turned out to be about 0.2 mm shorter than the true pole-to-equator fraction it was meant to represent.
The 1875 Treaty of the Meter created the CGPM and the BIPM to look after common standards, and in 1889 a platinum-iridium prototype bar took over; the original is still kept at the BIPM. In 1960 the meter was tied to 1,650,763.73 wavelengths of an orange-red krypton-86 line, and in 1983 to the speed of light, which made length a quantity derived from the time standard. The 2018 revision reworded that definition without changing the meter's size. NIST offers a handy yardstick for scale: a pace, meaning two steps, is roughly a meter or a yard.
The meter is the reference unit for length on this site.
Sources: BIPM: history of the metre; NIST: the meter and the SI redefinition; Wikipedia: Metre
Related conversions
- Meters to light-years (reverse)
- Light-years to kilometers
- Light-years to centimeters
- Light-years to millimeters
- Light-years to inches
- Light-years to feet
- Light-years to yards
- Light-years to miles
- Light-years to micrometers
- Light-years to nanometers
- Light-years to nautical miles
- Light-years to pixels (CSS)
- Kilometers to meters
- Centimeters to meters
- Millimeters to meters
- Inches to meters
- Feet to meters
- Yards to meters
- Miles to meters
- Micrometers to meters
- Nanometers to meters
- Nautical miles to meters
- Pixels (CSS) to meters
- Picometers to meters
See all length units.