Tens of thousands of miles? The planet's a little less than 8000 miles in diameter. As for "a few dozen meters", the Sudbury Neutrino Observatory was 2.1 kilome

Tens of thousands of miles? The planet's a little less than 8000 miles in diameter. As for "a few dozen meters", the Sudbury Neutrino Observatory was 2.1 kilometres down (at the nominal 6800 foot level in the old Creighton Mine).