Probably the MAC addresses of nearby wifi access points, compared to a big database of MAC address locations. Google do the same thing. If you switch wifi off and try again on a wired ethernet connection you'll probably find it becomes much less precise as it falls back to IP geolocation.
Now if RevK coded it, when it notices that it no longer has MAC-location to go on, it'll use the built-in accelerometers to determine if it moved. And what's to say that when Apple got the MAC-location, it wasn't also submitted as a hint to their IP geolocation database...?
Wifi positioning has become eerily accurate lately thanks to all the cellphones out there. Mapping wireless MAC addresses to location data.
I get exactly the same. There's a database out there of ip to location. See iplocation dot net
Correlated data from WiFi. This kind of data is known to Apple and has been part of their T&Cs for years. GPS on your phone + coarse location from cell-towers + local WiFi BSSIDs + RSSI Metering per BSSID from your MacBook = Fairly accurate correlated data feed of locations.Incidentally, if you were to transplant the BSSIDs local to you to the middle of a field, you'd still show up at home...
It's WiFi SSID based. There's been a lot of past controversy / noise about how much WiFi data Google slurp-up when they collect streetview photos.
Errm, what?it's wifi, mac addresses. Your iPhone has been sending data to Apple about your location. You've not heard of Skyhook? How did you not know about this?
So slightly trolling my own blog - I too assumed MAC address of WiFi.
Someone should tell Facebook: they think I am in Bracknell and Tamworth.
Could be worse; for me, most IP geolocation systems get the wrong *country*. (My ISP's netblock maps back to Essex - I'm up in Scotland, and not even the South end of it either.) WiFi it is, clearly!(Now I'm wondering if my Mac Mini will manage to locate itself, being connected over Ethernet with the WiFi interface turned off... It's not running Mavericks yet, though.)
Quite probably SSID, but... you know what my answer to the question would have been if I were Apple? The address on your Apple account
The blue 'halo' is >2m. The blue dot has you standing in the middle of the street. Strange place to check your e-mail ;)
Well, more than 2m, but not a lot more, I am in the corner of the house nearest the blue dot.
Have you noticed the even cooler feature that you can click the little share icon in the top left and send the location (or route) straight to any iOS device also on your iTunes account :) would be great if they implemented this for web pages in Safari...
My guess would have been that you had an iPhone with GPS in your pocket which was telling your Macbook where you were...
Apple (and Google) record the relationship of WiFi networks to GPS. Apple are also doing things with signal strength to estimate relative distances to low power Bluetooth 4 beacons (iBeacons) and very likely WiFi base stations. This is to enable indoor navigation and very localised advertising (knows when you pause in front of the sock counter).