Online Encyclopedia

EQUATION OF TIME

Online Encyclopedia
Originally appearing in Volume V09, Page 720 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!
EQUATION OF TIME, the difference between apparent time, determined by the meridian passage of the real sun, and mean time, determined by the passage of the mean sun. It goes through a double period in the course of a year. Its amount varies a fraction of a minute for the same date, from year to year and from one longitude to another, on the same day. The following table shows an average value for any date and for the Greenwich meridian for a number of years, from which the actual value will seldom deviate more than 20 seconds until after 1950. The + sign indicates that the real sun reaches the meridian after mean noon; the — sign before mean noon. Table of the Equation of Time. m. s. m. s. m. s. Jan. I + 3 26 Mar. I +12 39 May I -2 55 6 5 45 6 it 35 6 -3 27 II 7 51 II 10 20 II -3 46 16 9 43 i6 8 58 i6 -3 51 21 II 19 II 7 30 21 -3 40 26 12 36 26 5 59 26 -3 16 Feb. I +13 42 Apr. i + 4 9 June I -2 32 6 14 14 6 2 40 6 -1 44 lI 14 25 II + I 15 II —O 48 16 14 17 16—o 3 16+o 14 21 52 2I — I I2 21 I 19 26 i3 II 26 — 2 10 26 2 24 m. s. m. s. M 5. July I +3 26 Sept. I+ 0 9 Nov. -16 i8 6 4 21 6 — i 28 6 -16 19 it 5 8 II — 3 10 I I -15 58 16 5 44 16—4 55 i6—15 15 21 6 8 21 — 6 41 21 -14 12 26 6 18 26 — 8 25 26 -12 49 Aug. I +6 io Oct. 1 -10 5 Dec. I— I I 7 6 5 47 6 —II 38 6 — 9 9 II 5 9 `. II -13 2 II — 6 57 i6 4 17 16 -14 14 16 — 4 35 2I 3 I2 2I -15 ' I I 2I — 2 7 26 1 55 26 — 15 52 26 + 0 23
End of Article: EQUATION OF TIME
[back]
EQUATION OF THE CENTRE
[next]
EQUATOR (Late Lat. aequator, from aequare, to make ...

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.