To a perpendicular to the plane of ecliptic, the Earth’s axis of rotation makes an angle of 23¥2 degrees. Had this angle been 0 degree, which one among the following would result ?

The Earth's axial tilt of 23.5 degrees is the primary driver of seasonal changes and variations in day length [t1][t2]. If the tilt were 0 degrees (perpendicular to the ecliptic), the Sun would always be directly over the equator throughout the year. Consequently, there would be no seasons because the angle of insolation at any given latitude would remain constant [c2][t7]. Furthermore, the circle of illumination would always pass through the poles, resulting in the length of day and night being exactly equal (12 hours each) throughout the entire year [c4][t7]. This equality would apply to all locations on Earth, as the hemispheric bias caused by the tilt would be eliminated [c3][t10]. Therefore, all the listed consequences—no seasons, constant day length throughout the year, and uniform day length across the globe—would occur simultaneously.

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 12: Earth, Moon, and the Sun > 12.2.2 Seasons on the Earth > p. 177
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Midnight Sun > p. 253
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Lunar Nodal Cycle > p. 266
4. [4] https://education.nationalgeographic.org/resource/axis/