Physics
Skating on ice is possible because

The pressure on the ice due to skate raises its melting point
Ice is cold
The pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water
The surface of ice is smooth

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Physics
The earth is a

Non-absorber of heat
Bad absorber and bad radiator of heat
Good reflector of heat
Good absorber and good radiator of heat

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