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The lunar distance is on average approximately 385,000 km (239,000 mi), or 1.28 light-seconds; this is roughly 30 times Earth's diameter or 9.5 times Earth's circumference. Around 389 lunar distances make up an AU astronomical unit (roughly the distance from Earth to the Sun). Lunar distance is commonly used to express the distance to near ...
Average distance from Earth (which the Apollo missions took about 3 days to travel) – Solar radius: 0.005 – Radius of the Sun (695 500 km, 432 450 mi, a hundred times the radius of Earth or ten times the average radius of Jupiter) – Light-minute: 0.12 – Distance light travels in one minute – Mercury: 0.39 – Average distance from the ...
Comoving distance and proper distance. Comoving distance is the distance between two points measured along a path defined at the present cosmological time. For objects moving with the Hubble flow, it is deemed to remain constant in time. The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following ...
A light-year, alternatively spelled light year ( ly or lyr[ 3] ), is a unit of length used to express astronomical distances and is equal to exactly 9,460,730,472,580.8 km ( Scientific notation: 9.4607304725808 × 10 12 km), which is approximately 5.88 trillion mi.
Line-of-sight propagation. Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. [ 1] Electromagnetic transmission includes light emissions traveling in a straight line.
The kilometre, a unit of length, first appeared in English in 1810, [ 9] and the compound unit of speed "kilometers per hour" was in use in the US by 1866. [ 10] ". Kilometres per hour" did not begin to be abbreviated in print until many years later, with several different abbreviations existing near-contemporaneously. 1903: "KMph."
The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly 299 792 458 m (approximately 983 571 055 ft or 186 282 mi ). Just as the second forms the basis for other units of time, the light-second can ...
t. e. Travel time in seismology means time for the seismic waves to travel from the focus of an earthquake through the crust to a certain seismograph station. [1] Travel-time curve is a graph showing the relationship between the distance from the epicenter to the observation point and the travel time. [2] [3] Travel-time curve is drawn when the ...