The Sun: Man's Friend & Foe

[Montage of the 4 seasons] The seasons that we have here on earth are a visible reminder of another way that the Sun affects our lives. We generally think of having four seasons, Spring, Summer, Fall, and Winter; but some places on our planet think in terms of two seasons, Rainy and Dry. At the polar regions the seasons are different yet again due to their being located near the poles. Regardless of where you live and how you think of them the Sun is why we have the seasons.

Because the Earth is tilted on it's axis, the northern hemisphere receives more direct sunlight than the southern. This causes the change of the seasons. Many people think that the earth moves and changes its tilt. This is untrue. The earth remains tilted the same way all the time. However, as it revolves around the Sun the amount of exposure to the Sun changes because of the tilt. Take a look at this drawing to understand this principle.

[Diagram of Earth's tilt and seasons] The Sun doesn't travel due east to due west it travels in an arc pattern. In the northern hemisphere as winter gets gradually nearer the Sun's path shifts southward to a low arc which makes the days shorter and the nights longer. As summer approaches the Sun's path grows higher causing longer days and shorter nights. The results of this pattern are reversed for the southern hemisphere. But this predictable pattern is still where both hemispheres get their seasons from.

As the Earth orbits around the Sun, its axis points either toward the Sun or away from it. When the axis is pointing toward the Sun the northern hemisphere enjoys summer and six months later, when the axis is pointing away from the Sun, the southern hemisphere enjoys summer.

If the Earth's axis weren't tipped, not only would there not be any seasons but the southern hemisphere would be a huge icecap and the arctic would be more like the tropics. If the Earth's axis were tipped any more than it is the seasons would be more dramatic. Each year the polar ice caps would freeze and thaw causing the oceans to rise and fall significantly each year. This means that humans couldn't live on a large portion of the Earth that they now occupy as those areas would be flood zones. Our weather would also be a lot harsher and storms would last quite a bit longer than they do now.