Light-seconds to Meters (ls to m)
1 light-second equals 299,792,458 meters exactly.
How to convert light-seconds to meters
To convert light-seconds to meters, multiply the number of light-seconds by 299,792,458. This factor is exact. To go the other way, multiply meters by 3.335640952×10⁻⁹ (rounded).
meters = light-seconds × 299,792,458
Example: 10 light-seconds = 2,997,924,580 meters.
About these units
Light-second (ls)
The distance light travels in a vacuum in one second: 299,792,458 meters. The Moon is about 1.28 light-seconds from Earth.
Because the speed of light is now fixed at 299,792,458 meters per second, a light-second is exactly that many meters, with no uncertainty at all. Astronomers and radio engineers treat it as a convenient yardstick for distances that are small on the scale of the solar system but large on the scale of a laboratory. The abbreviation ls appears in tables of astronomical units, and it is not an official SI unit.
The Moon is the standard example: its average distance from Earth is about 1.282 light-seconds, which is why a radio exchange with a lunar mission has a noticeable round-trip lag of roughly two and a half seconds. The Earth's mean diameter is only about 0.0425 light-seconds, while the Sun's diameter is about 4.643. One astronomical unit is about 499 light-seconds. Sixty light-seconds make a light-minute, 3,600 make a light-hour, and 31,557,600 make a light-year, based on the Julian year.
1 light-second = 299,792,458 meters (exactly).
Sources: Wikipedia: Light-second; Wikipedia: Light-minute
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-seconds (reverse)
- Light-seconds to kilometers
- Light-seconds to centimeters
- Light-seconds to millimeters
- Light-seconds to inches
- Light-seconds to feet
- Light-seconds to yards
- Light-seconds to miles
- 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
- Light-years to meters
See all length units.