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Science 27 September 1991:
Vol. 253. no. 5027, pp. 1538 - 1541
DOI: 10.1126/science.253.5027.1538
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Articles

Ground-Based Near-Infrared Imaging Observations of Venus During the Galileo Encounter

D. CRISP 1, S. MCMULDROCH 2, S. K. STEPHENS 2, W. M. SINTON 3, B. RAGENT 4, K. -W. HODAPP 3, R. G. PROBST 5, L. R. DOYLE 6, D. A. ALLEN 7, and J. ELIAS 8

1 MS 169-237, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; visiting astronomer, Palomar Observatory, California Institute of Technology, Pasadena, CA 91125
2 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125; visiting astronomers, Las Campanas Observatory, Casilla 601, La Serena, Chile
3 Institute for Astronomy, University of Hawaii, Honolulu, HI 96822
4 San Jose State University Foundation, San Jose, CA 95192; visiting astronomer, University of Hawaii 0.6-m and 2.2-m telescopes at Mauna Kea Observatory, Mauna Kea, Hawaii
5 Kitt Peak National Observatory, Tucson, AZ 85719
6 National Aeronautics and Space Administration (NASA) Ames Research Center, Moffett Field, CA 94035; visiting astronomer, Kitt Peak National Observatory, Tucson, AZ 85719
7 Anglo-Australian Observatory, Post Office Box 296, Epping, New South Wales, Australia
8 Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile

Near-infrared images of Venus, obtained from a global network of ground-based observatories during January and February 1990, document the morphology and motions of the night-side near-infrared markings before, during, and after the Galileo Venus encounter. A dark cloud extended halfway around the planet at low latitudes (>±40°) and persisted throughout the observing program. It had a rotation period of 5.5 ± 0.15 days. The remainder of this latitude band was characterized by small-scale (400 to 1000 kilometers) dark and bright markings with rotation periods of 7.4 ± 1 days. The different rotation periods for the large dark cloud and the smaller markings suggests that they are produced at different altitudes. Mid-latitudes (±40° to 60°) were usually occupied by bright east-west bands. The highest observable latitudes (±60° to 70°) were always dark and featureless, indicating greater cloud opacity. Maps of the water vapor distribution show no evidence for large horizontal gradients in the lower atmosphere of Venus.

Revised on April 3, 1991
Accepted on July 17, 1991


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Wind Streaks on Venus: Clues to Atmospheric Circulation.
R. Greeley, R. Greeley, G. Schubert, D. Limonadi, K. C. Bender, W. I. Newman, P. E. Thomas, C. M. Weitz, and S. D. Wall (1994)
Science 263, 358-361
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A Global Traveling Wave on Venus.
M. D. Smith, P. J. Gierasch, and P. J. Schinder (1992)
Science 256, 652-655
   Abstract »    PDF »
Middle Infrared Thermal Maps of Venus at the Time of the Galileo Encounter.
G. S. Orton, G. S. ORTON, J. CALDWELL, A. J. FRIEDSON, and T. Z. MARTIN (1991)
Science 253, 1536-1538
   Abstract »    PDF »
Galileo Infrared Imaging Spectroscopy Measurements at Venus.
R. W. Carlson, R. W. CARLSON, K. H. BAINES, TH. ENCRENAZ, F. W. TAYLOR, P. DROSSART, L. W. KAMP, J. B. POLLACK, E. LELLOUCH, A. D. COLLARD, et al. (1991)
Science 253, 1541-1548
   Abstract »    PDF »


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