| 单词 |
parsec |
| 释义 |
parsec Astr.|ˈpɑːsɛk|
[f. parallax + second n.1]
A unit of length equal to the distance at which a star would have a heliocentric parallax of one second of arc, viz. 3·09 × 1016 metres (19·2 × 1012 miles, 3·26 light-years), approximately.
1913F. W. Dyson in Monthly Notices R. Astron. Soc. LXXIII. 342 There is need for a name for this unit of distance... Professor Turner suggests Parsec, which may be taken as an abbreviated form of ‘a distance corresponding to a parallax of one second’. 1921Glasgow Herald 11 July 4 He estimates the distance of the object as 140 parsecs or four times the distance of the Hyades cluster. 1955Sci. News Let. 29 Jan. 71/2 These hydrogen clouds have diameters of several parsecs, one parsec being the distance light travels in 3·26 years. 1962F. I. Ordway et al. Basic Astronautics vi. 290 Within 5 parsecs (16·5 light years) of the Sun, 53 individual stars have been counted, the nearest of which is Proxima Centauri, 25 trillion miles away. 1974S. V. M. Clube in R. H. Stoy Everyman's Astron. viii. 309 The nearest star clusters are the Pleiades and Hyades which are at distances of 130 and 40 parsecs respectively and therefore beyond the reach of trigonometric parallax determinations. 1977Time 30 May 42/2 The four of them are even now setting out to deliver the secret plans to rebel headquarters, light-years and parsecs away. |
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