Earth’s Tilt and Seasons
Tilt of Earth and Seasons
Up here on the board we have four circles which represent Earth. You notice first that the Earth does not travel in a circle it travels an ellipse. So, you would think right in the middle of the ellipse would be the sun, but actually the sun has shifted over a little bit so that it’s closer to one part of the ellipse than it is to others.
Over here we have what we call the perihelion and over here we have the aphelion. The perihelion is the closest point to the sun and the aphelion is the farthest point from the sun. Now, in no way is this supposed to be directly proportional to what it actually looks like.
This is just a way to give you an idea of what it looks like. The sun may actually be shifted a little bit over to the right. The point is here is that the sun, the earth is closer to the sun at some points than it is in others.
Now, you notice here this line right here which is the way the earth is tilted so the top of the earth right there directly north is right there and directly south is right there. Really, if the earth were to be straight up and down it would look like that.
What we have here is a 23.5 degree angle. 23.5 degrees. The earth is rotated at an angle of 23.5 degrees. We see it again here, and here, and here, each time it’s rotated 23.5 degrees. So, that’s how we get the different seasons.
Notice right here north is pointed away from the sun, but here north is pointed towards the sun. Right here we see north pointed toward the sun, that’s where it’s summer in the Northern Hemisphere.
Right here if we had earth, we have the Equator, up here is the Northern Hemisphere, and down here is the Southern Hemisphere. So, everything here is north. Everything else in the Southern Hemisphere is experiencing winter.
All of this area South America/Australia is experiencing winter at this time, because right here is south and the south is pointed away from the sun. So, if we’re getting heat from the sun and if the southern part of the earth is pointed away than it’s not getting any sun or it’s not getting as much sun.
Over here we see north pointed away from the sun and the south pointed towards the sun. It’s now just the opposite the north is experiencing winter and the south is experiencing summer.
Then up here, you may be wondering what that is, for the Northern Hemisphere this is autumn and for the Southern Hemisphere we have spring down here. You can see the four seasons right here represented by what part of the earth is pointing towards the sun. Again, the earth is always tilted at an axis of 23.5 degrees. So that’s a look at the tilt of earth and seasons.