Spend long enough on the Internet and you will likely be met with a post informing you that the speed of light is 299,792,458 meters per second, and the latitude of the Great Pyramid of Giza is 29.9792458°N, before inviting you to assess whether this is a coincidence or not.

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But is it true, and if so, is it a coincidence? 

The answer to the first question is yes. Light travels at 299,792,458 meters per second in a vacuum, the absolute speed limit of the universe. The latitude of the Great Pyramid of Giza is indeed 29.9792458 N – but so are a whole bunch of other places at the same latitude.

As for whether this is a coincidence or not, the answer is also yes. 

For a start the Ancient Egyptians – even if they had figured out the speed of light centuries ahead of its measurement by Danish astronomer Ole Roemer in 1676 CE and for some reason chose to keep quiet about it – did not work in meters, primarily because meters were not defined until 1791 CE.

As Snopes points out, Ancient Egyptians used cubits, with the speed of light being around 571,033,253 cubits per second. Had they had memes, maybe theirs would be talking about some random object in Western Russia at 57.1033253 latitude under the caption "COINCIDENCE??!"

As impressive as they were, the Ancient Egyptians did not measure the speed of light, nor navigate using global lines of longitude and latitude. And if they had done that, there'd probably be a little more evidence than positioning the Great Pyramid of Giza at a latitude that corresponds to the line of latitude when expressed in a measurement system centuries away from invention. 

All it is is a (slightly pleasing) coincidence.