1620 GEOGRAPHOS AND 433 EROS: SHAPED BY PLANETARY TIDES?
1620 GEOGRAPHOS AND 433 EROS: SHAPED BY PLANETARY TIDES?
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Date
1999
Authors
BOTTKE, W. F. JR.
RICHARDSON, D. C.
MICHEL, P.
LOVE, S. G.
Advisor
Citation
1620 Geographos and 433 Eros: shaped by planetary tides?
DRUM DOI
Abstract
Until recently, most asteroids were thought to be solid bodies whose shapes were determined largely
by collisions with other asteroids. Recent work by Burns and others has shown that many asteroids may
be little more than rubble piles, held together by self-gravity ; this means that their shapes may be
strongly distorted by tides during close encounters with planets. Here we report on numerical simulations
of encounters between an ellipsoid-shaped rubble-pile asteroid and Earth. After an encounter,
many of the simulated asteroids develop the same rotation rate and distinctive shape as 1620 Geographos
(i.e., highly elongated with a single convex side, tapered ends, and small protuberances swept
back against the rotation direction). Since our numerical studies show that these events occur with some
frequency, we suggest that Geographos may be a tidally distorted object. In addition, our work shows
that 433 Eros, which will be visited by the NEAR spacecraft in 1999, is much like Geographos, suggesting
that it too may have been molded by tides in the past.