[ETL]

"Rømer’s determination of the speed of light was the demonstration in 1676 that light has a finite speed, and so does not travel instantaneously.

The discovery is usually attributed to Danish astronomer Ole Rømer (1644–1710),[note 1] who was working at the Royal Observatory in Paris at the time.

By timing the eclipses of the Jupiter moon Io, Rømer estimated that light would take about 22 minutes to travel a distance equal to the diameter of Earth’s orbit around the Sun. This would give light a velocity of about 220,000 kilometres per second, about 26% lower than the true value of 299,792 km/s.

Rømer’s theory was controversial at the time he announced it, and he never convinced the director of the Paris Observatory, Giovanni Domenico Cassini, to fully accept it.

However, it quickly gained support among other natural philosophers of the period, such as Christiaan Huygens and Isaac Newton. It was finally confirmed nearly two decades after Rømer’s death, with the explanation in 1729 of stellar aberration by the English astronomer James Bradley."

https://en.wikipedia.org/wiki/R%C3%B8mer%27s_determination_of_the_speed_of_light

_________________________________________________________

[ETL]

[reed13k]

Wonder if he also accounted for the effect of the earth being closer/farther to Io having an additional/less pull by R^2

Would likely be miniscule-but the calculations they used to do were amazing considering they had no computers.

[Vermont Lt]

But it must be on a table top millions of miles away. Because it’s all flat. Isn’t it? //sarc

[Red Badger]

Smart dude.

Then, a century and a half later, Edgar Allen Poe explained why space is dark instead of light................

[Hot Tabasco]

What's amazing is that this was discovered over 300 years ago ...Just who educated these guys?

MIT wasn't around back then........

[A strike]

This is ridiculous !

EVERYone Knows that Muhammad discovered the speed of light !

[libertylover]

the demonstration in 1676 that light has a finite speed

That's amazing considering that Pink Floyd's "Dark Side of the Moon" wasn't released until 1973.

[Eagles6]

Just some Dead White Guy.

They ain't done nuthin'./sarc

[TalBlack]

Geez, should a light year be called a Romer???

[Paal Gulli]

There was a young lady named Bright
Whose speed was far faster than light;
She set out one day
In a relative way
And returned on the previous night.

— Arthur Henry Reginald Buller