What current is needed in the solenoid's wires?

A researcher would like to perform an experiment in a zero magnetic field, which means that the field of the earth must be cancelled. Suppose the experiment is done inside a solenoid of diameter 1.3 m, length 3.0 m, with a total of 6000 turns of wire. The solenoid is oriented to produce a field that opposes and exactly cancels the field of the earth.