Asteroids approaching the Earth from directions around the Sun |
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| Authors: | Syuzo Isobe and Makoto Yoshikawa |
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| Institution: | (1) National Astronomical Observatory, Mitaka, 181 Tokyo, Japan;(2) Communication Research Laboratory, Hirai, Kashima, 314 Ibaraki, Japan |
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| Abstract: | We have estimated close asteroid encounters with the Earth by numerical integrations of a system with the Sun, 9 planets, and 188 near-earth-asteroids during the period 1994–4600. Asteroids approach the Earth from directions within 30 around the Sun in more than 20% of encounters with the closest distance less than 0.01 AU. Since ground-based observations cannot detect these objects, we should develop space-borne and/or lunar observatories in a short time to allow enough warning time before a catastrophic collision. |
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