This Day, That Year – December 23

English astronomer, John Flamsteed, observed Uranus on this day in 1690 without realizing it was undiscovered.

Did you know that:

• Giovanni Cassini discovered Rhea, a satellite of Saturn, on this day in 1672
• Richard Arkwright, inventor of the spinning frame, was born on this day in 1732
• Thomas Edison patented a magneto-electric machine on this day in 1879