When was the Halley's Comet periodicity discovered?

More Questions:

What does "per capita" literally mean?

What number was retired by the Chicago Bulls to honor Michael Jordan?

What is better than paper in the paper, stone, scissors game?

What board game's tokens include a rope, a lead pipe, and a candlestick?

What is Demeter the god of?

Which Paul McCartney and Wings album includes "Picasso's Last Words"?

Who were the siblings of the Greek god Hera?

What position was first held by Kenesaw Mountain Landis?

Which character did Madeleine Martin play on the TV show "Californication"?

In "Family Guy', what does Peter put in Joe's water making him win the Special People's games?

Which film featured the song "Springtime for Hitler"?

Who replaced Vyacheslav Molotov as the leader of the Soviet Union in 1941?

What year was Albert Einstein born in?

What is it called when the liquid vapor pressure equals to the pressure of the gas above it?

Who created Rudolph the Red-Nosed Reindeer?