Earth's Orbital Mechanics and Solar Geometry

On 21st June (the Summer Solstice in the Northern Hemisphere), the Sun does not set below the horizon at the Arctic Circle. This is the time of the year when the North Pole is tilted maximum towards the Sun, causing the Sun to remain visible for 24 hours at the Arctic Circle (66.5°N). Option (b) is incorrect because 21st June is winter solstice in the Southern Hemisphere, so the Antarctic Circle experiences continuous darkness, not continuous sunlight. Option (c) is incorrect because on 21st June, the Sun shines vertically overhead at the Tropic of Cancer (23.5°N), not the Equator. Option (d) is incorrect for the same reason. > June 21 = Summer Solstice NH; Arctic Circle = 24-hour daylight; Tropic of Cancer = vertical noon sun. Answer: (a).