Sun (?), n. [OE. sunne,
sonne, AS. sunne; akin to OFries. sunne, D.
zon, OS. & OHG. sunna, G. sonne, Icel.
sunna, Goth. sunna; perh. fr. same root as L.
sol. √297. Cf. Solar, South.]
1. The luminous orb, the light of which
constitutes day, and its absence night; the central body round which
the earth and planets revolve, by which they are held in their orbits,
and from which they receive light and heat. Its mean distance from the
earth is about 92,500,000 miles, and its diameter about
860,000.
☞ Its mean apparent diameter as seen from the earth is
32′ 4″, and it revolves on its own axis once in 25⅓
days. Its mean density is about one fourth of that of the earth, or
1.41, that of water being unity. Its luminous surface is called the
photosphere, above which is an envelope consisting partly of
hydrogen, called the chromosphere, which can be seen only
through the spectroscope, or at the time of a total solar eclipse.
Above the chromosphere, and sometimes extending out millions of miles,
are luminous rays or streams of light which are visible only at the
time of a total eclipse, forming the solar corona.
2. Any heavenly body which forms the center of
a system of orbs.
3. The direct light or warmth of the sun;
sunshine.
Lambs that did frisk in the sun.
Shak.
4. That which resembles the sun, as in
splendor or importance; any source of light, warmth, or
animation.
For the Lord God is a sun and
shield.
Ps. lxxiv. 11.
I will never consent to put out the sun of
sovereignity to posterity.
Eikon Basilike.
Sun and planet wheels (Mach.), an
ingenious contrivance for converting reciprocating motion, as that of
the working beam of a steam engine, into rotatory motion. It consists
of a toothed wheel (called the sun wheel), firmly secured to
the shaft it is desired to drive, and another wheel (called the
planet wheel) secured to the end of a connecting rod. By the
motion of the connecting rod, the planet wheel is made to circulate
round the central wheel on the shaft, communicating to this latter a
velocity of revolution the double of its own. G. Francis.
-- Sun angel (Zoöl.), a South
American humming bird of the genus Heliangelos, noted for its
beautiful colors and the brilliant luster of the feathers of its
throat. -- Sun animalcute. (Zoöl.)
See Heliozoa. -- Sun bath
(Med.), exposure of a patient to the sun's rays;
insolation. -- Sun bear (Zoöl.),
a species of bear (Helarctos Malayanus) native of Southern
Asia and Borneo. It has a small head and short neck, and fine short
glossy fur, mostly black, but brownish on the nose. It is easily
tamed. Called also bruang, and Malayan bear. --
Sun beetle (Zoöl.), any small
lustrous beetle of the genus Amara. -- Sun
bittern (Zoöl.), a singular South American
bird (Eurypyga helias), in some respects related both to the
rails and herons. It is beautifully variegated with white, brown, and
black. Called also sunbird, and tiger bittern. --
Sun fever (Med.), the condition of fever
produced by sun stroke. -- Sun gem
(Zoöl.), a Brazilian humming bird (Heliactin
cornutus). Its head is ornamented by two tufts of bright colored
feathers, fiery crimson at the base and greenish yellow at the tip.
Called also Horned hummer. -- Sun grebe
(Zoöl.), the finfoot. -- Sun
picture, a picture taken by the agency of the sun's
rays; a photograph. -- Sun spots
(Astron.), dark spots that appear on the sun's disk,
consisting commonly of a black central portion with a surrounding
border of lighter shade, and usually seen only by the telescope, but
sometimes by the naked eye. They are very changeable in their figure
and dimensions, and vary in size from mere apparent points to spaces
of 50,000 miles in diameter. The term sun spots is often used
to include bright spaces (called faculæ) as well as dark
spaces (called maculæ). Called also solar spots.
See Illustration in Appendix. -- Sun
star (Zoöl.), any one of several species of
starfishes belonging to Solaster, Crossaster, and allied
genera, having numerous rays. -- Sun trout
(Zoöl.), the squeteague. -- Sun
wheel. (Mach.) See Sun and planet wheels,
above. -- Under the sun, in the world; on
earth. "There is no new thing under the sun." Eccl. i.
9.
☞ Sun is often used in the formation of compound
adjectives of obvious meaning; as, sun-bright, sun-
dried, sun-gilt, sunlike, sun-lit, sun-
scorched, and the like.