Page 174 - 89 history of astronomy_opt
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Later he employed the same method with
the comets of 1577, 1580, 1582, 1585, 1590,
1593, and 1596, and proved that they too
had no measurable parallax and must be
very distant.
The startling discovery that stars are
not necessarily permanent, that new stars
may appear, and possibly that old ones may
disappear, had upon him exactly the same
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