Search results
Results From The WOW.Com Content Network
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 miles).
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).
Distance light travels in one Julian year (365.25 days) — Oort cloud: 75 000: ± 25 000: Distance of the outer limit of Oort cloud from the Sun (estimated, corresponds to 1.2 light-years) — Parsec: 206 265 — One parsec. The parsec is defined in terms of the astronomical unit, is used to measure distances beyond the scope of the Solar ...
The largest unit for expressing distances across space at that time was the astronomical unit, equal to the radius of the Earth's orbit at 150 million kilometres (93 million miles). In those terms, trigonometric calculations based on 61 Cygni's parallax of 0.314 arcseconds, showed the distance to the star to be 660 000 astronomical units (9.9 ...
The siriometer is an obsolete astronomical measure equal to one million astronomical units, i.e., one million times the average distance between the Sun and Earth. [13] This distance is equal to about 15.8 light-years, 149.6 Pm, or 4.8 parsecs, and is about twice the distance from Earth to the star Sirius. [14]
The exact modern SI definition is "[The second] is defined by taking the fixed numerical value of the cesium frequency, Δν Cs, the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s −1." [1] Historically, many units of time were defined by ...
miles per second: 186 000: miles per hour [1] 671 000 000: astronomical units per day: 173 [Note 1] parsecs per year: 0.307 [Note 2] Approximate light signal travel times; Distance: Time: one foot: 1.0 ns: one metre: 3.3 ns: from geostationary orbit to Earth: 119 ms: the length of Earth's equator: 134 ms: from Moon to Earth: 1.3 s: from Sun to ...
Different from instantaneous speed, average speed is defined as the total distance covered divided by the time interval. For example, if a distance of 80 kilometres is driven in 1 hour, the average speed is 80 kilometres per hour. Likewise, if 320 kilometres are travelled in 4 hours, the average speed is also 80 kilometres per hour.