| |
|
No. The Moon (and maybe other objects too) slows it down. Actually, here's an interesting letter to Nature outlining another factor. Quite old, so there should be some new data out there.
Discontinuous Change in Earth's Spin Rate following Great Solar Storm of August 1972
JOHN GRIBBIN* & STEPHEN PLAGEMANN†
*Nature, 4 Little Essex Street, London WC2R 3LF
†NASA Goddard Space Flight Center, Institute for Space Studies, 2880 Broadway, New York, NY 10025
THE question of a link between changes in the Earth's spin rate and the activity of the Sun is of topical interest, and there is good evidence that the changing length of day is influenced by the mean level of solar activity1,2. The possibility of a one-to-one correlation between specific events on the Sun and specific changes in the length of day has remained more controversial, however, although there was a suggestion of such an effect associated with the great solar storm of 1959 (refs. 3−5) Specifically, Danjon suggested3−5 that there was an increase in the length of day when the nucleonic component of solar cosmic rays increased ; this was in addition to the usual steady increase in the length of day. Other observers questioned the reality of this effect (for a discussion of the controversy see ref. 6), and because the 1959 solar storm was the greatest recorded since the time of Galileo, there was no immediate hope of an independent test of Danjon's claim. In August 1972, however, an even greater disturbance occurred on the Sun7−9. It seemed to us that this might provide the ideal opportunity to resolve the controversy, and we have indeed found a discontinuous change in the length of day, and a change in the rate of change of the length of day (a glitch) immediately after that event. Changes in the length of day, and thus in the spin rate of the Earth, are revealed by regular measurements of Universal Time (UT) carried out at many observatories around the world. For our purpose, we are interested in UT2, the version of Universal Time with the effects of the Chandler Wobble and seasonal variations removed. The difference between Atomic Time (AT) and UT2 shows, on average, a monotonic increase as the Earth's spin slows down and the length of day increases.
References 1. Challinor, R. A., Science, 172, 1022 (1971).
2. Gribbin, J., Science, 173, 558 (1971).
3. Danjon, A., CR Acad. Sci. Paris., 254, 2479 (1962).
4. Danjon, A., CR Acad. Sci. Paris., 254, 3058 (1962).
5. Danjon, A., Notes et Informations de l'Observatoire de Paris, 8 No. 7 (1962).
6. Schatzman, E., in The Earth–Moon System (edit. by Cameron A. G. W., and Marsden, B. G.), 12 (Plenum, New York, 1966).
7. Pomerantz, M. A., and Duggal, S. P., Nature, 241, 331 (1973).
8. Chupp, E. L., Forrest, D. J., Higbie, P. R., Surie, A. N., Tsai, C., and Dunphy, P. P., Nature, 241, 333 (1973).
9. Mathews, T., and Lanzerotti, L. J., Nature, 241, 335 (1973).
10. Macdonald, N. J., and Roberts, W. O., J. Geophys. Res., 65 529 (1960).
11. Roberts, W. O., and Olsen, R. M., J. Atmos. Sci., 30, 135 (1973). |
|
|
