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I see the bug. If the ping times are high enough (~250ms) it will happily create circles which exceed the area of earth, and the google maps API will happily draw negative circles which exclude the user's likely location.

Really there should be a max function that shades the entire earth (or ignores it since that result really can't tell you anything).

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If ping times are over 250ms the user's likely location is China (but could also be online via satellite, or in space). Of course, if the user is in China, Google Maps won't display.

Eh? RTT between London and Sydney for example is around 300ms and testing that page, I see a 316ms RTT from Singapore (in London).

Theoretical minimum RTT's based on the speed of light for systems on the opposite side of the world is nice and all but doesn't take into account the realities of packet processing on the internet.

..and those of actual cable routing (esp. on land), and the speed of light in fiber vs. vacuum, that alone adding 66ms for a great circle.

Yes but speaking statistically, since virtually nobody lives in Australia or London versus China, the user's likely location is China.

Or they're on Comcast with wifi in a large apartment building. I have a 250mS ping, and I'm definitely not in China.

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