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The light year is often used to measure distances to stars: A light year is not a unit of timeFor alternate uses of "time", see Time (disambiguation). Time quantifies or measures the interval between events, or the duration of events. Time has long been perceived as a dimension in which each event has a definite (but not necessarily unique) positi. In astronomyAstronomy which etymologically means " law of the stars," (from Greek: + nomos) is a science involving the observation and explanation of events occurring outside Earth and its atmosphere. It studies the origins, evolution, physical and chemical propertie, the preferred unit of measurement for such distances is the parsecThis article is about the unit of length. In computer programming, Parsec is an XML syntax analyzer, like Lark, or a parsing library for the Haskell programming language. There's an open source computer game named Parsec . The parsec (abbreviated pc is a which is defined as the distance at which an object will generate one arcsecondA second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. 7E-7 of a circle. It is the angular diameter on object of 1 unit diameter at a distance of 360 of parallaxParallax is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. Or more simply put, it is the apparent shift of an object against a background due to a change in observ when the observing object moved one astronomical unitThe astronomical unit AU is a unit of distance, approximately equal to the mean distance between Earth and Sun. The currently accepted value of the AU is 149,597,870,691+-30 metres (about 150 million kilometres or 93 million miles). Earth's orbit is not a. This is equal to approximately 3.26 light years. The parsec is preferred because it can be more easily derived from, and inter-compared with, observational data.
A light year is also equal to 63,241 astronomical units (AU). For a list of lengths on the order of one light year, see the article 1 E15 mTo help compare different distances this page lists lengths starting at 1015 m (1,000,000 million km). See also lengths of other orders of magnitude. Distances shorter than 1015 m 7 500 000 million km 50 000 AU Inner radius of Oort cloud 9 500 000 million.
Units related to the light year are the light minute and light secondA 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 exact, since the metre is actually defined in terms of the light second. A light minute is 6, the distance light travels in a vacuum in one minute and one second, respectively. A light minute is equal to 17,987,547,480 m. Since light travels 299,792,458 m in one second, a light second is 299,792,458 m in length.