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Science 12 December 1997:
Vol. 278. no. 5345, pp. 1921 - 1924
DOI: 10.1126/science.278.5345.1921
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Reports

Radar Detection of the Nucleus and Coma of Comet Hyakutake (C/1996 B2)

J. K. Harmon, * S. J. Ostro, L. A. M. Benner, K. D. Rosema, R. F. Jurgens, R. Winkler, D. K. Yeomans, D. Choate, R. Cormier, J. D. Giorgini, D. L. Mitchell, dagger P. W. Chodas, R. Rose, D. Kelley, M. A. Slade, M. L. Thomas

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.

J. K. Harmon, National Astronomy and Ionosphere Center, Arecibo Observatory, Post Office Box 995, Arecibo, PR 00614, USA.
S. J. Ostro, L. A. M. Benner, K. D. Rosema, R. F. Jurgens, R. Winkler, D. K. Yeomans, D. Choate, R. Cormier, J. D. Giorgini, D. L. Mitchell, P. W. Chodas, R. Rose, D. Kelley, M. A. Slade, M. L. Thomas, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA.
*   To whom correspondence should be addressed.

dagger    Present address: Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA.

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