On this day in science history: 25 May

From the days of ancient technology to modern science - find out what happened on this day in the history of science.

25th May 2017
Halley's Comet © Harvard College Observatory/Science Photo Library/Getty Images

Halley's Comet © Harvard College Observatory/Science Photo Library/Getty Images

240 BC – First recorded sighting of Halley’s Comet

The first certain perihelion passage of Halley’s Comet is recorded in China.

The sighting fits Edmond Halley’s computed orbit, who realised that comets seen in 1531, 1607 and 1682 were the same one. Halley’s Comet comes close to Earth about every 75 years, with the next sighting due in 2061.

Listen: Witness - Soviet Mission to Halley's Comet

1842 – Idea of Doppler Effect proposed

Christian Doppler © Imagno/Getty Images
Christian Doppler © Imagno/Getty Images

The idea of the Doppler Effect is presented to the Royal Bohemian Society, Prague by Austrian physicist Christian Doppler.

The Doppler Effect occurs when an emitted wave (sound, light or other) changes in frequency when the source or observer moves in relation to one another. The frequency increases as they move towards one another, and decreases as they move further apart. This has been used to explain the change in pitch of a passing siren and redshift in astronomy.

1940 – Penicillin first tested on mice

Technicians refining penicillin in a laboratory (1943) © Daily Herald Archive/Getty Images
Technicians refining penicillin in a laboratory (1943) © Daily Herald Archive/Getty Images

Four mice recover from lethal bacterial infection after being injected with penicillin.

Penicillin was tested by Howard Florey and Ernst Chain, who inoculated eight mice a lethal dose of the Streptococcus bacteria. Four of the mice were then injected with penicillin who all survived, while the others died. Penicillin was the first antibiotic used to successfully treat infectious diseases, and now comprises a whole group of antibiotics.

Listen: Drugs that Changed the World: Penicillin

1961 – JFK announces plan to put a man on the Moon

President John F. Kennedy addresses Congress and proclaims that the USA should land a man on the Moon by the end of the decade.

Discover more history of science

 


Follow Science Focus on TwitterFacebook and Google+

You are currently reading: On this day in science history: 25 May - 25th May