| 释义 |
light-year
light′-year`
n. 1. the distance traversed by light in one mean solar year, about 5.88 trillion mi. (9.46 trillion km): used as a unit in measuring stellar distances. 2. light-years, a. a very great distance, esp. in development or progress: Today's computers are light-years ahead of older ones. b. a very long time. [1885–90] light-year (līt′yîr′) The distance that light travels in a vacuum in one year, equal to about 5.88 trillion miles (9.48 trillion kilometers).Usage It is important to remember that a light-year is a measure of distance, not time. A light-year is the length of empty space that light can traverse in a year, close to six trillion miles. When scientists calculate how many light-years the stars are from Earth or from one another, they are calculating their distance, not their age.Thesaurus| Noun | 1. | light-year - the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometerslight yearastronomy unit - a linear unit used for astronomical distanceslight hour - the distance light travels in a vacuum in one hour; approximately one billion kilometerslight minute - the distance light travels in a vacuum in one minute; approximately 18 million kilometerslight second - the distance light travels in a vacuum in one second; approximately 300,000 kilometers |
Translationslight1 (lait) noun1. the brightness given by the sun, a flame, lamps etc that makes things able to be seen. It was nearly dawn and the light was getting stronger; Sunlight streamed into the room. 光 光2. something which gives light (eg a lamp). Suddenly all the lights went out. 燈 灯3. something which can be used to set fire to something else; a flame. Have you got a light for my cigarette? 點火物 点火物4. a way of viewing or regarding. He regarded her action in a favourable light. 見解 见解 adjective1. having light; not dark. The studio was a large, light room. 明亮的 明亮的2. (of a colour) pale; closer to white than black. light green. 淡色的 淡色的 verb – past tense, past participle lit (lit) , ˈlighted – 1. to give light to. The room was lit only by candles. 照亮 照亮2. to (make something) catch fire. She lit the gas; I think this match is damp, because it won't light. 點燃 点燃ˈlightness noun 光亮 光亮ˈlighten verb to make or become brighter. The white ceiling lightened the room; The sky was lightening. 照亮 照亮ˈlighter noun something used for lighting (a cigarette etc). 打火機 打火机ˈlighting noun a means of providing light. The lighting was so bad in the restaurant that we could hardly see. 照明設備 照明lighthouse noun a building built on rocks, coastline etc with a (flashing) light to guide or warn ships. 燈塔 灯塔ˈlight-year noun the distance light travels in a year (nearly 9.5 million million kilometres). 光年 光年bring to light to reveal or cause to be noticed. The scandal was brought to light by the investigations of a journalist. 顯露，揭露 显露，揭露 come to light to be revealed or discovered. The manuscript came to light in a box of books at an auction. 顯露，出現 暴露in the light of taking into consideration (eg new information). The theory has been abandoned in the light of more recent discoveries. 考慮到 鉴于，由于，按照 light up1. to begin to give out light. Evening came and the streetlights lit up. 亮起 点着2. to make, be or become full of light. The powerful searchlight lit up the building; She watched the house light up as everyone awoke. 照亮 照亮3. to make or become happy. Her face lit up when she saw him; A sudden smile lit up her face. 使滿面春風，喜形於色 使变得喜悦，使兴奋起来 see the light1. to be born, discovered, produced etc. After many problems his invention finally saw the light (of day). 出生，出現，問世 出世，出现，问世 2. to be converted to someone else's point of view etc. 領悟 领悟set light to to cause to begin burning. He set light to the pile of rubbish in his garden. 點燃 点燃light-year
light-year, in astronomy, unit of length equal to the distance lightlight,
visible electromagnetic radiation. Of the entire electromagnetic spectrum, the human eye is sensitive to only a tiny part, the part that is called light. The wavelengths of visible light range from about 350 or 400 nm to about 750 or 800 nm.
..... Click the link for more information. travels in one sidereal yearsidereal year,
time required for the earth to complete an orbit of the sun relative to the stars. The sidereal year is 365 days, 6 hr, 9 min, 9.5 sec of mean solar time (see solar time).
..... Click the link for more information. . It is 9.461 × 1012 km (about 6 million million mi). Alpha CentauriAlpha Centauri
, brightest star in the constellation Centaurus and 3d-brightest star in the sky; also known as Rigil Kent or Rigil Kentaurus; 1992 position R.A. 14h39.1m, Dec. −60°49'. Its apparent magnitude is −0.26.
..... Click the link for more information. and Proxima Centauri, the stars nearest our solar system, are about 4.3 light-years distant. See also parsecparsec
[parallax + second], in astronomy, basic unit of length for measuring interstellar and intergalactic distances, equal to 206,265 times the distance from the earth to the sun, 3.26 light-years, or 3.08 × 1013 km (about 19 million million mi).
..... Click the link for more information. .light-year (l.y.) A unit of distance equal to the distance traveled through space in one year by light, radio waves, or any other form of electromagnetic radiation. Since all electromagnetic radiation travels in a vacuum at the speed of light, one light-year equals about 9.4605 × 1012 km. Distances expressed in light-years give the time that radiation would take to cross that distance. One light-year equals 0.3066 parsecs, 63 240 astronomical units, or a parallax of 3.259 arc seconds. Analogous but smaller units of distance, such as the light-month, light-week, light-day, and light-second are also used, often to indicate the size of an object (such as the core of an active galaxy) whose output is varying: the timescale of the variations imposes an upper limit on the size, the conditions being unlikely to change more quickly than the time it takes for light to travel across the region. light-year[′līt ‚yir] (astrophysics) A unit of measurement of astronomical distance; it is the distance light travels in one sidereal year and is equivalent to 9.461 × 1012 kilometers or 5.879 × 1012 miles. MedicalSeelight year |