Question

What line of latitude is the northernmost point on earth that receives direct light from the sun?

Answer 1

Not positive on what you are asking here.

Explanation:

If by direct light from the sun you mean the sunlight reaching the Earth, all latitudes will receive sunlight at some point in time. In fact the North Pole receives 6 straight months of sunlight followed by 6 months of darkness.

If you mean what latitude does the sun rays strike at 90 degrees, that would be the Tropic of Cancer or approx 23.5 degrees N latitude (it varies). The definition of the location of the Tropic of Cancer is the northern most latitude that the sun's rays strike at a 90 degree angle.