The Sun's Position at Noon on 21st June

To determine the correct answer, let's understand the concept of the Sun's position at noon on 21st June and its relation to the Earth's tilt and equator.

Earth's Tilt and Seasons
- The Earth is tilted on its axis by approximately 23.5 degrees.
- This tilt causes the change in seasons as the Earth orbits around the Sun.
- When the North Pole is tilted towards the Sun, it is summer in the Northern Hemisphere, and when the South Pole is tilted towards the Sun, it is winter in the Northern Hemisphere.

The Equator
- The equator is an imaginary line that divides the Earth into the Northern Hemisphere and the Southern Hemisphere.
- It is located at 0 degrees latitude and is equidistant from the North Pole and the South Pole.

The Sun's Position on 21st June
- On 21st June, the Sun reaches its highest point in the sky at noon.
- This position is known as the Sun being "overhead" or "at zenith."
- The Sun is directly overhead at different latitudes during different times of the year due to the Earth's tilt.

Analysis of Options
a) The equator
- The equator is located at 0 degrees latitude.
- Since the Earth's tilt causes the Sun's position to change throughout the year, the Sun is not directly overhead at the equator on 21st June.
- Hence, option a) is incorrect.

b) 23.5 degree N
- This latitude is located in the Northern Hemisphere.
- The Earth's tilt causes the Sun to be directly overhead at the Tropic of Cancer, which is at approximately 23.5 degrees north.
- Therefore, option b) is correct.

c) 23.5 degree S
- This latitude is located in the Southern Hemisphere.
- The Earth's tilt causes the Sun to be directly overhead at the Tropic of Capricorn, which is at approximately 23.5 degrees south.
- Therefore, option c) is incorrect.

d) 66.5 degree N
- This latitude is located in the Arctic Circle.
- The Earth's tilt causes the Sun to be directly overhead at the Arctic Circle during the summer solstice, which occurs around 21st June.
- Therefore, option d) is incorrect.

Conclusion
- The correct answer is option b) as the Sun is directly overhead at approximately 23.5 degrees north on 21st June, known as the Tropic of Cancer.