Page 525 - 89 history of astronomy_opt

white spot beside it completed a rotation in
ˆ
less time by 5A minutes than the red spot–
a difference of 260 miles an hour. Thus
they came together again every six weeks,
but the motions did not continue uniform.
The spot was feeble in 1882-4, brightened
in 1886, and, after many changes, is still
visible.
Galileo’s great discovery of Jupiter’s four
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