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A faint streak of light recorded in 1955 has calmed fears about a
catastrophic asteroid impact. After learning of the possible threat to Earth
posed by asteroid 1999 AN10
(This Week, 5 June, p 5), two German amateur
astronomers, Arno Gnädig and Andreas Doppler, calculated where it should
have been during the 1955 Palomar sky survey. They then spotted it on a
digitised image. From this information, Gareth Williams and Brian Marsden of the
Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, refined
their calculations of the asteroid’s orbit. “We’re safe until sometime after
2076,” says Marsden.