Seasons and Axial Tilt
Why summer is hot: a matter of angle, not distance
Summary
The seasons are caused not by our distance from the Sun but by the Earth's axis, tilted by 23.5°. Because the axis always points in the same direction in space, different hemispheres receive sunlight at a steeper angle at different times of the year.
In depth
A common misconception says that we are closer to the Sun in summer and further away in winter. The truth is the opposite: the Earth is closest to the Sun (perihelion) in early January, that is, during the northern hemisphere's winter. The only mechanism that explains the seasons is this: the Earth's spin axis is tilted 23.5° to its orbital plane, and the axis points in an almost fixed direction in space (near the Pole Star). As the Earth moves to different parts of its orbit over the year, the axis leans toward or away from the Sun. At the summer solstice (21 June for the north), the north pole leans toward the Sun; days in this hemisphere are long and the light arrives at a steep angle: summer. At the winter solstice (21 December) it is the other way round. At the equinoxes between the two solstices (21 March, 23 September) the axis is perpendicular to the Sun-Earth line, and both hemispheres have equal day and night.
Rate Seasons and Axial Tilt
What did you think of this content? Click the stars to leave your rating.
Leave a Comment and Rating