Re: Leap-16 ... Oh SHIT !

On Wed, 08 Jul 2026 17:50:30 GMT, Charlie Gibbs wrote:

> For many things, 300,000 is close enough.

Ole Rømer’s original measurement, from around 1676, was more like
200,000 kilometres per second, as I recall. (Inaccuracies in the known
orbits of the planets at the time etc.)

Even that was a massive improvement. Before that, people had no idea
whether light was infinite or just very fast, and if so, how fast it
was -- a million times faster than sound? A million million?

And Rømer made the discovery entirely by accident: he was trying to
measure the timing of the eclipses of Jupiter’s moon Io, and noticed
that there was a cyclic variation which would have had a period of
about 13 months (Wikipedia doesn’t mention this detail, as far as I
can see).

Once we had a ballpark figure, other researchers were able to pin
things down more precisely, because we now had a good idea where to
look for further measurements.