EQUATION OF TIME

refers to the difference between mean and apparent solar time, caused by the fact. that the sun moves at a varying rate, The everyday unit of time is that of an imaginary sun moving at the average rate of the real.sun. Mean and apparent noon differ by a varying amount known as the equation of time. In the Nautical Almanac this equation is given for every day in the year. Four’ times in a year —on or about April 15, June 15, Sept. 1; and Dec. 24—the equation is zero, since on those occasions apparert and mean noon coincide. BQUATOR, imaginary line drawn round center of earth’s surface; divides earth into’ N. and S. hemispheres; latitudes are méasured from the e., its’ own latitude being’ 0°. Celestial Equator is the great circle of the heavens coinciding with plane of earth equator; also calléd The EHqwinectial, because, during sun’s cro ing of it, day and night’ ave exactly equal-in length.