Page:The Music of the Spheres.djvu/191

 this Belt note that there is more to be seen here than meets the unaided eye, for suspended from either side, like an added attempt at decoration, hang tiny stars of different sizes, daintily colored. Mintaka (δ), the double star on the west, is a white and pale violet, of the 2nd and the 7th magnitudes. Alnitak (ζ) on the lower end to the southeast, is a topaz-yellow, light purple and gray, of the 2nd, 6th and 10th magnitudes. The faint star just below Alnitak is composed of an exquisite group of delicate stars of various colors.

If the north pole of our earth was shot out like a dart, it would hit the dome of our sky somewhere in the vicinity of the North Star. Likewise, if the earth's equator could be conceived of as swelling and swelling and swelling, it would hit Orion just about at the top star of his belt. The circular line where this imaginary terrestrial hoop would fit against the heavens is called the celestial equator and it, of course, is in a position equally distant between the two heavenly poles. A good way to remember just where the celestial equator passes is noticing the pathway which the star mentioned above traces in its journey from east to west. A teacher of astronomy would now add that not only is the terrestrial equator marked as the celestial equator in the sky, but every meridian of the 'swollen' earth is traced up there as an hour circle, all of the hour circles being fastened in a great framework to both poles, as they are on earth. But instead of latitude the astronomer says declination, and in place of longitude he says right ascension, just as in place of meridian, he says hour circle. He then can designate the places of the stars in the sky in exactly the manner in which he designates the position of a sea or a city on the earth and as large telescopes are provided with equatorial mountings, so that their axes conform with that of our earth, objects in the sky can be located by the use of graduated circles and verniers, thus greatly facilitating astronomical research.