Meters to Light-seconds (m to ls)
1 meter equals 3.335640952×10⁻⁹ light-seconds (rounded).
How to convert meters to light-seconds
To convert meters to light-seconds, multiply the number of meters by 3.335640952×10⁻⁹. The factor is rounded to 10 significant digits. To go the other way, multiply light-seconds by 299,792,458.
light-seconds = meters × 3.335640952×10⁻⁹
Example: 10 meters = 3.335640952×10⁻⁸ light-seconds.
About these units
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
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
Related conversions
- Light-seconds to meters (reverse)
- Meters to kilometers
- Meters to centimeters
- Meters to millimeters
- Meters to inches
- Meters to feet
- Meters to yards
- Meters to miles
- Meters to micrometers
- Meters to nanometers
- Meters to nautical miles
- Meters to pixels (CSS)
- Meters to light-years
- Kilometers to light-seconds
- Centimeters to light-seconds
- Millimeters to light-seconds
- Inches to light-seconds
- Feet to light-seconds
- Yards to light-seconds
- Miles to light-seconds
See all length units.