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Science 15 December 1989:
Vol. 246. no. 4936, pp. 1450 - 1454
DOI: 10.1126/science.246.4936.1450
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Articles

Photometry from Voyager 2: Initial Results from the Neptunian Atmosphere, Satellites, and Rings

Arthur L. Lane 1, Robert A. West 1, Charles W. Hord 2, Robert M. Nelson 1, Karen E. Simmons 2, Wayne R. Pryor 2, Larry W. Eposito 2, Linda J. Horn 1, Brad D. Wallis 1, Bonnie J. Buratti 1, Thomas G. Brophy 2, Padma Yanamandra-Fisher 1, Joshua E. Colwell 2, David A. Bliss 1, Marvin J. Mayo 1, and William D. Smythe 1

1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
2 Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309

The Voyager photopolarimeter successfully accomplished its objectives for the Neptune encounter, performing measurements on the planet, several of its satellites, and its ring system. A photometric map of Neptune at 0.26 micrometer (µm) shows the planet to be bland, with no obvious contrast features. No polar haze was observed. At 0.75 µm, contrast features are observed, with the Great Dark Spot appearing as a low-albedo region and the bright companion as being substantially brighter than its surroundings, implying it to be at a higher altitude than the Great Dark Spot. Triton's linear phase coefficients of 0.011 magnitudes per degree at 0.26 µm and 0.013 magnitudes per degree at 0.75 µm are consistent with a solid-surface object possessing high reflectivity. Preliminary geometric albedos for Triton, Nereid, and 1989N2 were obtained at 0.26 and 0.75 µm. Triton's rotational phase curve shows evidence of two major compositional units on its surface. A single stellar occultation of the Neptune ring system elucidated an internal structure in 1989N1R, in the sim50-kilometer region of modest optical depth. 1989N2R may have been detected. The deficiency of material in the Neptune ring system, when compared to Uranus', may imply the lack of a "recent" moon-shattering event.

Submitted on November 2, 1989
Accepted on November 15, 1989


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
An Explanation for Neptune's Ring Arcs.
C. C. Porco and C. C. PORCO (1991)
Science 253, 995-1001
   Abstract »    PDF »
Voyager 2 at Neptune: Imaging Science Results.
B. A. Smith, B. A. Smith, L. A. Soderblom, D. Banfield, c. Barnet, A. T. Basilevsky, R. F. Beebe, K. Bollinger, J. M. Boyce, A. Brahic, et al. (1989)
Science 246, 1422-1449
   Abstract »    PDF »
Ultraviolet Spectrometer Observations of Neptune and Triton.
A. L. Broadfoot, S. K. Atreya, J. L. Bertaux, J. E. Blamont, A. J. Dessler, T. M. Donahue, W. T. Forrester, D. T. Hall, F. Herbert, J. B. Holberg, et al. (1989)
Science 246, 1459-1466
   Abstract »    PDF »


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