We are all familiar with waves; from ripples on the surface of a pond to the swell of the ocean. A wave is just a regular vibration that travels through something, like air or water. Sound is one type of wave. When someone speaks, the waves are made in their throat and travel out to the listener's ear. It is then the ear's job to change that wave in the air into a signal that can be understood by the brain. Sound waves need support - a medium - to travel.

Annie Jump Cannon

Annie Jump Cannon
Credit: Smithsonian Institution (US)

Occupation: Astronomer and Curator

Year born: 1863

Research Areas: Stars, Stellar Classification, Spectroscopy


"In our troubled days it is good to have something outside our planet, something fine and distant for comfort"