Question

Which planet experiences constant daylight or darkness for 42 years at its poles?

Answer 1

Any planet with a significant tilt, including Earth, has continuous day and then continuous night at the poles. But Uranus does that everywhere (or close to it) because of its unusual amount of tilt.

Explanation:

On Earth the axial tilt is about 23 degrees so the continuous day and continuous night, lasting for a maximum of half the orbital period at each pole, are limited to within that 23 degrees from either pole. That's where we get the Arctic and Antarctic circles from. On Uranus, the tilt is almost exactly 90 degrees, so the equivalent of the Arctic and Antarctic circles lie close to the equator. Thus in effect almost all of Uranus is "Arctic" or "Antarctic".