A light second is a unit of length. It is defined as the distance light travels in an absolute vacuum in one second or 299,792,458 metres. Note that this value is considered exact, since the metre is actually (as of 1983) defined in terms of the light second. It is just over 186,282 miles and almost 10⁹ feet. A unit of length is a way of measuring length or distance. ... Distance is a numerical description of how far apart things lie. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength [citation needed]. The elementary particle that defines light is the photon. ... Look up Vacuum in Wiktionary, the free dictionary. ... Look up second in Wiktionary, the free dictionary. ... To help compare different orders of magnitude, this page lists lengths starting at 108 m (100 Mm or 100,000 km). ... The metre, or meter (US), is a measure of length. ... A mile is the name of a unit of length, usually used to measure distance, in a number of different systems, including English units, Imperial units, United States customary units and Norwegian/Swedish mil. ... This article is about a foot as a unit of length. ...

A light minute is 60 light seconds and a light hour is 60 light minutes or 3600 light seconds. A light year is 31,557,600 light seconds. A light minute (also written light-minute) is a unit of length. ... A light hour (also written light-hour) is a unit of length. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ...

Some distances in light seconds:

• The mean diameter of the Earth is 0.0425 light seconds.
• The mean distance, over land, between opposite sides of the planet Earth is 0.0668 light seconds (which also means that communications between opposite sides of the planet, taking a circumferential path, can never travel faster than about 67 milliseconds).
• The average distance from the Earth to the Moon is 1.282 light seconds.
• The diameter of the Sun is about 4.643 light seconds.
• The average distance from the Earth to the Sun (or 1 astronomical unit) is 499.0 light seconds or 8.317 light minutes.

It is also possible to add diminutive prefixes, such as the light nanosecond, equal to almost exactly 30 cm (11.8 in or nearly a foot). Earth (IPA: , often referred to as the Earth, Terra, or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Earth (IPA: , often referred to as the Earth, Terra, or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Bulk composition of the Moons mantle and crust estimated, weight percent Oxygen 42. ... The Sun is the star of our solar system. ... The astronomical unit (AU or au or a. ... To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ...

See also

• Light minute
• Light year
• Speed of light
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