[AS.] One of the bright bodies seen in the sky at night, whose distance is so great that as seen from the earth they appear only as points of light. By astronomers the stars are looked upon as the suns of remote systems. Like our sun, they emit light; and when the spectroscope is applied to the light which they give out, it is found that the materials of which the stars are composed agree with those known to be present in the sun and in our earth. The distance of the stars is so great that when viewed from the earth they are always seen in the same direction ; hence, as they maintain an invariable position relative to each other, they have been named fixed stars. This term is used in a comparative and not an absolute sense, as it is known that many of them are in a state of motion, although it can be perceived only by delicate observations. They are divided into classes, according to their apparent brightness. These are termed magni-. tudes. The brightest stars are said to be of the first magnitude, those that fall short of this of the second, and so on. Down to the sixth or seventh magnitude the stars are visible to the naked eye, and from the eighth to the sixteenth by powerful telescopes. The three or four brightest classes are distributed with tolerable uniformity over the celestial sphere; but of the total amount visible to the naked eye and by means of the telescope, by far the larger number are in or near the Milky Way. In certain parts of the heavens the stars are collected into groups in a more condensed manner than in neighboring parts. Such groups are called clusters. One well-known group is called the Pleiades, in which six or seven stars may be noticed by the naked eye, but which photography has shown to consist of 2,326. Many nebulae that were formerly thought to be masses of glowing gas have been recently found to be clusters of stars so remote that their individual members are imperceptible except with instruments of great power. Photography has revealed stars so far distant that a message sent 1,900 years ago would only have just reached them, and would be still on the way to others, going with the speed of light, or 186,000 miles a second.