This Day That Year

May 10

in History

First Sunspot Recorded — Chinese astronomers spot a blemish on the sun
ChinaAncient
28

First Sunspot Recorded

Chinese astronomers spot a blemish on the sun

During the Han dynasty, Chinese astronomers peered at the sun and recorded what appears to be the first precisely dated observation of a sunspot in human history. Using jade rings and other filtering methods, they documented a dark mark on the solar disc, noting it with meticulous care. This observation, made more than two thousand years ago, demonstrates the extraordinary sophistication of ancient Chinese astronomy and began humanity's long quest to understand our nearest star.

28 BC
Cecilia Payne Was Born — She revealed what the stars are made of
Wendover, EnglandEarly 20th Century
1900

Cecilia Payne Was Born

She revealed what the stars are made of

In Wendover, England, Cecilia Helena Payne was born -- the woman who would make one of the most brilliant discoveries in astrophysics. Her 1925 doctoral thesis at Harvard demonstrated that stars are composed primarily of hydrogen and helium, overturning the prevailing assumption that their composition mirrored Earth's. Initially dismissed, her conclusion was later proven correct and is now considered one of the most important findings in the history of astronomy.

1900 AD
Sony — Sony introduces the Betamax videocassette recorder.
Late 20th Century
1975

Sony

Sony introduces the Betamax videocassette recorder.

Sony introduces the Betamax videocassette recorder.

1975 AD