## Shop Windows to the Universe

We now offer the Cool It! card game in our Science Store. Cool It! is the new card game from UCS that teaches kids about the choices we have when it comes to climate change.

Picture of Christian Doppler
The University of St. Andrews, Scotland

# Christian Doppler

Christian Doppler was an Austrian mathematician who lived between 1803-1853. He is known for the principle he first proposed in Concerning the coloured light of double stars in 1842. This principle is now known as the Doppler Effect. He hypothesised that the pitch of a sound would change if the source of the sound was moving.

Doppler's hypothesis was tested by Buys Ballot in 1845. He used two sets of trumpeters: one set stationary at a train station and one set moving on an open train car. Both sets of musicians had perfect pitch and held the same note. As the train passed the station, it was obvious that the frequency of the two notes didn't match, even though the musicians were playing the same note. This proved Doppler's hypothesis.

Later, a scientist named Fizeau generalized Doppler's work by applying his theory not only to sound but also to light.

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## Science, Evolution, and Creationism

How did life evolve on Earth? The answer to this question can help us understand our past and prepare for our future. Although evolution provides credible and reliable answers, polls show that many people turn away from science, seeking other explanations with which they are more comfortable....more

## The Doppler Effect

The Doppler effect was named after Christian Doppler, who first came up with the idea in 1842. He learned that sound waves would have a higher frequency if the source was moving toward the observer and...more

## Wave Beats

Sound travels in waves. You hear sound because waves hit your ear. Sound waves are similar to ocean waves. They both have a certain frequency. The frequency is measured in hertz, which is one cycle per...more

## Charles Darwin

Charles Darwin was an English Naturalist who lived between 1809-1882. He laid the foundations for the modern science of biology, and changed how other scientists understood the appearance of life on Earth....more

## Christian Doppler

Christian Doppler was an Austrian mathematician who lived between 1803-1853. He is known for the principle he first proposed in Concerning the coloured light of double stars in 1842. This principle is...more

## Ben Franklin

Ben Franklin was an American scientist and statesman who lived between 1706-1790. At a time when little was known about electricity, he carried out many experiments to learn of its dangers and possible...more

## Edmond Halley

Edmond Halley was an English astronomer who lived between 1656-1742. Using historical records, his own observations, and Newton's universal law of gravitation, he reasoned that the comets which had appeared...more

## William Herschel

William Herschel was born in Germany and lived in England as he worked as an astronomer. He lived between 1738-1822. He built high magnification telescopes that let him observe the heavens with greater...more

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