| 释义 |
ˈsunspot
Also sun-spot.
1. Path. A spot or marking on the skin caused by exposure to the sun.
1818–20E. Thompson Cullen's Nosologia (ed. 3) 333 Ephelis; Sun Spots. 1872–4Jefferies Toilers of Field (1892) 262 Her brown but clear cheek, free from freckles and sun-spots.
2. Astron.
a. A spot or patch on the disk of the sun, appearing dark by contrast with the brighter general surface, and constituted by a cavity in the photosphere filled with cooler vapours.
Sunspots occur only in a zone extending 45° on each side of the sun's equator, often in groups, and last from a few hours to several months; their diameter varies from about 100 to about 100,000 miles; their frequency shows a marked period of about 11 years, corresponding to a periodicity of magnetic and possibly other phenomena on the earth.
1868Lockyer Elem. Astron. §121 Its [sc. the magnetic needle's] greatest oscillations occurring when there are most sun-spots. 1878Newcomb Pop. Astron. iii. ii. 248, 1882, 1893, etc., will be years of numerous sun-spots. 1894W. L. Dallas in Indian Meteorol. Mem. VI. 2 The maximum rainfall agreeing approximately with the maximum sunspots.
b. attrib. Also sunspot cycle, the recurring increase and decrease in the number of sunspots, with a period averaging just over 11 years.
1883Science I. 462/1 The maximum of auroras corresponds with the minimum sun-spot period. 1884H. F. Blanford in Indian Meteorol. Mem. (1894) VI. 2 The epoch of sun⁓spot maximum approximately coincides with that of minimum pressure. 1913H. H. Turner in Monthly Notices R. Astron. Soc. Dec. 89 The main Sun-spot swarm was in perihelion in 1816–7. 1922H. S. Jones Gen. Astron. v. 126 There is a remarkable connection between the Sun-spot cycle and the occurrence of magnetic storms on the Earth. 1977Jrnl. R. Soc. Arts CXXV. 157/1 Since the solar output appears to change by a good deal less than 1 per cent, even during solar flares, it is not surprising that weather events show very little correlation with the sunspot cycle.
3. Cinemat. A powerful arc lamp used to imitate the light from the sun in colour cinematography; = sun arc s.v. sun n.1 13 a.
1930[see sun arc s.v. sun n. 13 a]. 1976H. R. F. Keating Filmi, Filmi, Inspector Ghote iii. 29 We are using a great number of different lights for different purposes in filming, Five-Ks, Two-Ks, Sunspots, Solars, Babies.
4. A place that affords plentiful sunshine.
1976U.S. News & World Rep. 2 Feb. 26/1 Most travelers favor sun spots. St. Maarten, in the Netherlands Antilles, leads the parade. 1983Listener 6 Jan. 36/3 (Advt.), First choose your holiday sun-spot, then choose where to stay.
Hence ˈsunspottery [-ery 2], humorous or contemptuous term for the subject or theory of sunspots, esp. of their connexion with terrestrial phenomena.
1882R. A. Proctor in Standard 27 Nov. 2/4, I doubt whether even a twelfth of the astronomers of our time favour ‘Sunspottery’. |