The sun's rays strike earth at their northernmost and southernmost positions
winter and summer solstices
spring and fall equinoxes
lunar eclipses
solar eclipses

This is a clever question.

The sun always illuminates 50% of the Earth ... 24/7/365 .

The northernmost place on Earth is the north pole. 
It is illuminated from March 21 to September 21 ...
continuously for half of the year between the equinoxes.

The southernmost place on Earth is the south pole. 
It is illuminated from September 21 to March 21 ...
continuously for the other half of the year between
the equinoxes.

The only times when both the northernmost and southernmost
places are illuminated by the sun are the times of the two
equinoxes ... March 21 and September 21.

What even is this. where is the question