16 / 20
The main reason for the Earth’s seasons is the…
  • A
    length of the day, as stated by Kepler’s second law.
  • B
    elliptical orbit of the Earth around the Sun.
  • C
    distance between the Sun and the Earth.
  • D
    inclination of the Earth’s polar axis to the plane of the ecliptic.

It is a common misconception that the changes of seasons are governed by the Earth’s distance from the Sun. This is not true. As the Sun’s heat is transmitted radially, the effect of the distance change between 91.4 million statute miles at perihelion and 94.6 million statute miles at aphelion would only be to change the amount of heat received by the Earth by about 3%, not enough to explain the marked changes between the summer and winter.

The predominant cause of the Seasons is the inclination (tilt) of the earth. The Earth’s axis is inclined (tilted) at an angle of 66.5° to its orbit stated as 23.5° to the normal to the orbital plane (90°- 66.5° = 23.5°).

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.