Kilometers to Light-hours (km to lh)
1 kilometer equals 9.265669311×10⁻¹⁰ light-hours (rounded).
How to convert kilometers to light-hours
To convert kilometers to light-hours, multiply the number of kilometers by 9.265669311×10⁻¹⁰. The factor is rounded to 10 significant digits. To go the other way, multiply light-hours by 1,079,252,849 (rounded).
light-hours = kilometers × 9.265669311×10⁻¹⁰
Example: 10 kilometers = 9.265669311×10⁻⁹ light-hours.
About these units
Kilometer (km)
1,000 meters. The standard unit for road distances in most countries.
A name for 1,000 meters took a while to settle. In 1793 France's National Convention made the metre the sole French unit of length, and the first proposed name for the thousand-metre multiple was millaire. Everyday French usage then leaned on the myriametre, 10,000 meters, well into the 1800s. The Netherlands adopted the kilometre in 1817, under the local name mijl, and made it the only official unit of that size in 1867. In 1935 the CIPM dropped the myria- prefix, which left the kilometre as the standard unit for road-scale distances.
Kilo- is the SI prefix for a thousand, and the kilometre is now the preferred unit for land distances in most of the world, with the United States, the United Kingdom and Liberia among those that still use the mile. One kilometre is about 0.621 mile. The main span of Lisbon's 25 de Abril Bridge, at 1.013 km, gives a sense of the scale. Even its pronunciation has been argued over: in 1970 Australia's Metric Conversion Board made stress on the first syllable official, although Prime Minister Gough Whitlam argued for stress on the second. Military slang in several countries calls it a klick.
1 kilometer = 1,000 meters (exactly).
Sources: Wikipedia: Kilometre; Wikipedia: Metric prefix; BIPM: history of the metre
Light-hour (lh)
The distance light travels in an hour (about 1.08 billion km). Pluto is about 4.8 light-hours from the Sun.
Reaching the outer planets takes light hours rather than minutes, and the light-hour is the matching unit. Equal to 3,600 light-seconds, it is exactly 1,079,252,848,800 meters, or about 1.08 billion kilometers. Like the other light-time units it is informal, defined entirely by the fixed speed of light and the length of the SI second rather than by any standards body, and it appears mainly in astronomy outreach and in descriptions of deep-space missions.
Neptune orbits at about 30 astronomical units, which with light taking roughly 499 seconds per unit works out to somewhat over four light-hours. Pluto, at an average of 34.72 astronomical units, is about 4.81 light-hours from the Sun. The Voyager 1 probe passed 23 light-hours from Earth and the Sun by 2025 and is expected to reach one light-day, 24 light-hours, around late 2026. Beyond that scale the light-day, light-week and light-year take over.
1 light-hour = 1,079,252,848,800 meters (exactly).
Sources: Wikipedia: Light-hour; Wikipedia: Light-minute; Wikipedia: Astronomical unit
Related conversions
- Light-hours to kilometers (reverse)
- Kilometers to meters
- Kilometers to centimeters
- Kilometers to millimeters
- Kilometers to inches
- Kilometers to feet
- Kilometers to yards
- Kilometers to miles
- Kilometers to micrometers
- Kilometers to nanometers
- Kilometers to nautical miles
- Kilometers to pixels (CSS)
- Kilometers to light-years
- Meters to light-hours
- Centimeters to light-hours
- Millimeters to light-hours
- Inches to light-hours
- Feet to light-hours
- Yards to light-hours
- Miles to light-hours
See all length units.