Sidereus Nuncius
Galileo's First Jupiter Observations (2 of 4)
January 21, at 30 minutes
January 22, at the second hour
Io and Europa appear to be too close for Galileo's instrument to split, based on most of his other observations. He may have experienced exceptionally good seeing that night, but more likely, he misreported the time of his observation. Note the difference only four hours makes, below.
January 22, at the sixth hour
January 23, 40 minutes after sunset
January 23, at the fifth hour
Galileo writes, ...the two stars which [four hours] earlier were closer to
Jupiter were no longer visible, hiding behind Jupiter in my opinion...
January 24
January 24, at the sixth hour
Galileo writes, If I am not mistaken, the two middle little stars seen
earlier had united into one.
January 25, at 1 hour 40 minutes
January 26, at 0 hours 40 minutes
January 26, at the fifth hour
Galileo writes, Then at the fifth hour...near Jupiter a fourth star had
emerged on the east...elevated a little to the north above the straight
line...
January 27, at 1 hour after sunset
Ganymede transits Jupiter while Europa hides in its shadow.
January 30, at the first hour
January 31, at the second hour
January 31, at the fourth hour
February 1, at the second hour
