.jpg)
Print
Email
People puzzled over the reason for the seasons for centuries. Not anymore!
The Earth's Tilt
In one year, Earth revolves completely around the Sun while rotating on an invisible axis, like a tilted, spinning top.
- At one end of the axis is the North Pole; at the other, the South Pole.
- The axis is tilted at a 23.5° angle away from the Sun during winter in the Northern Hemisphere; it's the opposite in the summer.
Seasons are determined by the direction of Earth's tilt in relation to the Sun and the angle of the Sun's light as it strikes Earth.
The Equator's Position
The equator is an imaginary line dividing Earth into the Northern and Southern Hemispheres. On 2 days each year, on or around March 21 and September 23, the Sun is directly above the equator. Here is how the equator relates to the seasons:
- In the Northern Hemisphere, spring starts on the March date, which is called the vernal equinox.
- Fall begins on the September date, which is called the autumnal equinox.
- Summer in the Northern Hemisphere begins on or around June 21, the summer solstice, when the Sun is directly above an imaginary line 23.5° north of the equator called the Tropic of Cancer.
- Winter begins on or around December 21, the winter solstice, when the Sun is above the Tropic of Capricorn, 23.5° south of the equator.
- The seasons are the opposite in the Southern Hemisphere.
Seasonal Facts
Here are some seasonal facts—the long and the short of it, as it were.
- The summer solstice is one of the longest days of the year in the Northern Hemisphere—and the day when there is no sunlight at the South Pole.
- The winter solstice is one of the shortest days of the year in the Northern Hemisphere—and the day when there is no sunlight at the North Pole.
- Daytime and nighttime on the equinoxes are not equal; this is a myth. However, within a few days of each equinox, there is a day with nearly equal daytime and nighttime. (This depends on the latitude.)
Find the exact time of day that the solstices and equinoxes occur on our Seasons page.
More Articles:
.png)
