Chapter 1
The search for Planet X
Chapter 2
The heart of Pluto
Chapter 3
The weird worlds of the Kuiper Belt
Chapter 4
The great planet debate
Chapter 5
Beyond the icy frontier
YOUR GOAL
Master of Pluto and the icy worlds of the Kuiper Belt
Ch 1 · The search for Planet X
artiteacher The search for Planet X
Are we finding Planet X? (Not yet, no!) / But we found Pluto! (Watch it blink and glow!)
artiteacher A self-taught farm boy discovered Pluto using a blinking star comparator.
Fun Fact
Pluto's cash prize: The 11-year-old girl who named Pluto received five British pounds as a reward, worth about 300 dollars today.
Glossary
blink comparator (noun)
An astronomical instrument used to detect motion by rapidly alternating between two photographs of the same star field. Clyde Tombaugh used this device at Lowell Observatory to discover Pluto in February 1930.
An astronomical instrument used to detect motion by rapidly alternating between two photographs of the same star field. Clyde Tombaugh used this device at Lowell Observatory to discover Pluto in February 1930.
Quiz
What device did Clyde Tombaugh use to spot Pluto's movement across star photos?