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Science 28 July 1967:
Vol. 157. no. 3787, pp. 423 - 425
DOI: 10.1126/science.157.3787.423
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Articles

Resonance Rotation of Venus

Irwin I. Shapiro 1

1 Lincoln Laboratory, Massachusetts Institute of Technology, Lexington

Combination of two types of radar data shows the orbital plane and equator of Venus to be included by less than 2 degrees, and the sidereal rotation period to be 243.09 ± 0.18 days (retrograde)—remarkably close to the 243.16-day period for which the spin would be in resonance with the relative orbital motions of Earth and Venus. In this resonance, Venus would make, on average, four axial rotations as seen by an Earth observer between successive close approaches of the two planets. Estimates of the instantaneous spin period, accurate within about 0.01 day, would provide important information on the difference of Venus's equatorial moments of inertia, on their orientation, and on the magnitude of the tidal torque exerted on Venus by the sun.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Venus: Mass, Gravity Field, Atmosphere, and Ionosphere as Measured by the Mariner 10 Dual-Frequency Radio System.
H. T. Howard, H. T. Howard, G. L. Tyler, G. Fjeldbo, A. J. Kliore, G. S. Levy, D. L. Brunn, R. Dickinson, R. E. Edelson, W. L. Martin, et al. (1974)
Science 183, 1297-1301
   Abstract »    PDF »
Venus: Radar Determination of Gravity Potential.
I. I. Shapiro, I. I. Shapiro, G. H. Pettengill, G. N. Sherman, A. E. E. Rogers, and R. P. Ingalls (1973)
Science 179, 473-476
   Abstract »    PDF »
Venus: Topography Revealed by Radar Data.
D. B. Campbell, D. B. Campbell, R. B. Dyce, R. P. Ingalls, G. H. Pettengill, and I. I. Shapiro (1972)
Science 175, 514-516
   Abstract »    PDF »
Venus: The Next Phase of Planetary Exploration.
D. M. Hunten, D. M. Hunten, and R. M. Goody (1969)
Science 165, 1317-1323
   PDF »
Polar Temperature of Venus.
W. A. Gale, W. A. Gale, and A. C. E. Sinclair (1969)
Science 165, 1356-1357
   Abstract »    PDF »
Spin-Orbit Resonance of the Inner Planets.
P. M. Campbell (1969)
Science 165, 930
   PDF »
Venus: An Isothermal Lower Atmosphere?.
W. Gale, W. Gale, M. Liwshitz, and A. C. E. Sinclair (1969)
Science 164, 1059-1060
   Abstract »    PDF »
Venus Clouds: Test for Hydrocarbons.
W. T. Plummer and W. T. Plummer (1969)
Science 163, 1191-1192
   Abstract »    PDF »
Venus: Lower Atmosphere Not Measured.
V. R. Eshleman, V. R. Eshleman, G. Fjeldbo, J. D. Anderson, A. Kliore, and R. B. Dyce (1968)
Science 162, 661-665
   Abstract »    PDF »
Rotation of Venus.
I. I. Shapiro (1968)
Science 159, 1124
   PDF »
Radar Astronomy: Rotation rates of Venus and Mercury and density of the atmosphere of Mars are recent radar discoveries.
V. R. Eshleman (1967)
Science 158, 585-597
   PDF »


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