Scintillation

Collier's New Encyclopedia (1921)

a twinkling of the stars; a familiar phenomenon to all who have directed their attention to the firmament above us. Under ordinary atmospheric conditions this flickering is possessed only by the so-called fixed stars. A planet shines steadily and by this mark can readily be picked out. When near the horizon, however, planets have been observed to scintillate slightly; while stars at low altitudes invariably twinkle more vigorously than stars overhead. This at once points to the atmosphere as an important factor, since the phenomenon is more pronounced when the light has to traverse a greater depth of air. Again, when viewed through sufficiently large telescopes stars cease twinkling altogether. The action of the telescope is to concentrate on the eye a much larger pencil of rays than could naturally enter it. Instead of one slender ray the eye receives the integral effect of a great number of rays, whose individual features are lost in the general average. In the case of a planet, again, the rays which fall on the retina converge from all parts of a disk of sensible size; and in the integral effect of this pencil the individual half of the 4th century B. C. One of his earliest works was the temple of Athena Alea at Tegea in Arcadia, on the site of a previous one burned down in 395 b. c. Some 15 years or so later he settled in Athens, where for more than a quarter of a century he labored at his profession. Toward the end of his life he was associated with Leochares and others in preparing sculpture for the great mausoleum of Halicarnassus in Asia Minor. A large composition, representing Achilles being convoyed to Leucæ by Poseidon, Thetis, and the Nereids, preserved for some time in the temple of Neptune at Rome, was accounted one of his masterpieces. He excelled also in statues of single gods and goddesses. SCORBUTUS. See SCURVY.