NEARLY 90 per cent of the 104 comets that the SOHO spacecraft has discovered
close to the Sun in the past four years are small fragments of a single giant
comet.
Astronomers believe they are descendants of a giant comet that broke up,
possibly the one observed by the Greek historian Ephorus in 372 BC. The
fragments break up every time their 800-year orbit takes them past the Sun, says
Doug Biesecker, a SOHO scientist at the NASA Goddard Space Flight Center in
Greenbelt, Maryland.
Biesecker believes the fragments broke into icy chunks measuring less than 50
metres in diameter the last time the comet鈥檚 remains passed close to the Sun.
This time as they came within 700 000 kilometres of the Sun, says Biesecker,
鈥渢hey鈥檝e all just completely evaporated鈥�.
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