What did Robert Hooke observe using the earliest Gregorian telescope he built in 1673?
The rotations of Mars and Jupiter
The surface of the Moon
The rings of Saturn
The Andromeda Galaxy
Answer
In 1673, Robert Hooke built the earliest Gregorian telescope and used it to observe the rotations of the planets Mars and Jupiter. This was a significant contribution to the field of astronomy.
The Brilliant Mind of Robert Hooke: Unveiling the Legacy of an English Polymath