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What is Eratosthenes famous for measuring?
Earth’s circumference
How did Eratosthenes measure Earth’s size?
By comparing shadows at two locations
What tool did Eratosthenes mainly use to make his calculations?
A gnomon or stick for measuring shadows
Which country did Eratosthenes live in?
Ancient Greece (in Egypt at the Library of Alexandria)
What assumption did Eratosthenes make about the Sun’s rays?
That they arrive at Earth parallel to each other
What scientific idea is Doppler known for?
The Doppler effect
What happens to sound waves when something moves toward you?
The waves compress and frequency increases
What happens to light from stars moving away from Earth?
It becomes red-shifted
What everyday example demonstrates the Doppler effect?
An ambulance siren changing pitch as it passes
What does the Doppler effect help astronomers measure?
Whether stars and galaxies are moving toward or away from us
What gas did Priestley discover?
Oxygen
How did Priestley discover oxygen?
By heating mercury oxide with sunlight
What effect did Priestley notice when mice breathed oxygen?
They lived longer and were more active
What important process did Priestley discover with plants?
Plants release oxygen
What did Priestley use to test his gas samples?
Candles and animals (like mice)
