
Speed of light and Moon distance from an occultation of Mars by the Moon - ColinWright
http://arxiv.org/abs/1506.00346
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ISL
An excellent effort; proper execution of experiments is independent of the
sensitivity. It's very inexpensive to get good at the science and art of
experiment itself. Proper execution is the hardest part; improved sensitivity
is in significant part a question of available resources (cleverness is
significant, too).

(The precision-metrology part of me feels compelled to point out that any
absolute measurement of the speed of light using this method should include an
estimation of the covariance of the result (and its uncertainties) with the
variation of the assumed value of c used by GPS for timing and position
determination).

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nathancahill
That, and the citizen science movement helps tremendously. It's what I love
most about eBird[0]. Thousands of people collecting observations (with varying
degrees of accuracy) provide a wider and more accurate picture than any number
of scientists could deliver on their own.

[0] [http://ebird.org/content/ebird/](http://ebird.org/content/ebird/)

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nathancahill
Hey asanagi, if you see this, you've been shadowbanned. I feel bad since
you've been posting decent comments.

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asanagi
What a fascinating paper! Although I know the speed of light is finite and
have considered many of the implications of relativity, I never thought of the
effects on the apparent occultation of two celestial bodies at significant
distances from one another relative to the observer. The moon's transit
between Earth and Mars would not appear reciprocally the same to observers on
both planets. Obvious in retrospect, but the layman does not tend to consider
relativistic effects in this kind of simple geometric reasoning.

There's enough distance between us and the Moon that if you had a flashlight
bright enough, you could easily perceive the delay between switching it on and
seeing the Moon's surface brighten, as the light made the return trip.
Something to think about next time you look up at the Moon and wonder about
its scale and distance.

