The Midnight Sun is a phenomenon experienced by observers North of the Arctic circle during Summer Solstice where the Sun can be seen circling over and around 360 degrees without ever setting. Depending how far North the observer is, the Sun can be seen for several days/weeks, rising and falling as usual but never fully setting beyond the horizon. This is because the Sun having reached the Tropic of Cancer is making its tightest, narrowest circle over the Earth, so much so that observers positioned centrally within the Arctic circle are never at any time significantly far enough away from the Sun for it to set beyond their horizon. Not until after Summer Solstice when the Sun makes its way back towards the equator will the Sun set completely and Arctic days begin getting shorter.
Meanwhile in the Antarctic during Summer Solstice, the Sun disappears completely for over 2 months leaving everyone below the Antarctic circle in bitter cold darkness from mid-May to mid-July. Again, this is because the Sun narrowing and tightening its path towards the Tropic of Cancer means it has moved significantly far enough away from the Antarctic perimeter so as not to be seen by observers positioned so far South. Not until mid-July when the Sun expands and widens its path back significantly far enough will Antarctic observers again be able to see the Sun above the horizon and the Antarctic days begin getting longer.