Geodetic annual variation of the sidereal day

✍ Scribed by A.D. Fokker

• Publisher: Elsevier Science
• Year: 1957
• Weight: 134 KB
• Volume: 23
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(57)96432-7

✦ Synopsis

Owing to the geodetic precession of parallel axes, effect of Einstein's theory of gravitation 1),. the sidereal day will be shorter than the proper terrestrial day. The difference will amount to ~ m/r of the difference between mean solar day and sidereal day (237 sec), where m is the gravitation parameter ~f the sun, expressed as a length (1,47 kin) and r the radius of the earth's orbit (1,5 • l08 kin). The earth's orbit being an ellipse (1/r = (1 + e cos 9)/a) with eccentricity e = 1/60, the geodetic fluctuation amplitude in the difference of sidereal and proper terrestrial day will amount to 237 sec e • ~ m/a = 6 nanosecond. In the spring the sidereal clock will be 3,44/~ sec fast, in the autumn as much slow.

Recent data on the seasonal irregularities of the earth's rotation point to a fluctuatiou of about 27 millisec.