Have you ever noticed that most globes (like the one below) are sitting at an angle? It's because the globe maker was trying to accurately depict Earth as being slightly tilted. If you ever see a globe that is not tilted, it is another example of #FakeGeography.
Globe

If the Earth’s axis were not tilted, every day would be pretty much the same as every other day. The sun would always be in the same positions in the sky and every day of the year would be 12 hours long (12 hours of light and 12 hours of darkness). However, the earth’s axis is tilted 23 ½ degrees away from perpendicular. This tilt sets up the changing seasonal patterns of sun angle and length of day.

There are four key reasons for the seasons. The first two are important for determining the length of a year or day. The third and fourth reasons are the most important when explaining why we have changing seasons in Indianapolis. These 4 key reasons are:

1) Earth's revolution around the sun. The Earth’s revolution determines the timing of the seasons and, of course, the length of a year (365.25 days -- extra 0.25 days is noted by the additional day in February during Leap Year). We're moving around the Sun at about 66,000+ miles per hour, but of course, we don't feel that because of the pull of gravity.

2) Earth's daily rotation. Every single day (24 hours) the Earth rotates (from west to east) or spins one time on its axis. This means that as the Earth moves in its path around the sun, it is also rotating.

Further, at all times on Earth, we have 50% day and 50% night. The line or edge that separates the half of Earth with daylight from the other half of Earth experience night is called the Circle of Illumination. This is visualized in the following 13-second video.

Although not terribly important or related to other concepts, the Earth's rotation velocity or speed is fastest along the Equator and then slows going poleward (toward the North and South Pole). At both the North and South Poles, the Earth's rotational velocity is 0 (zero miles per hour). In a subsequent chapter, I will introduce the term "Coriolis force", which is a result of these characteristics of Earth's rotation.

3) The axial tilt of the Earth. The Earth is tilted 23.5 degrees, which is a number you have seen (and will continue to see) in these early chapters. If the Earth did not have this tilt, there would be no seasons. In the following 24-second video, I visualize the Earth's axial tilt.

4) Axial parallelism. As our Earth rotates on its tilted axis, the axis maintains its alignment throughout the entire revolution around the sun. This is a bit of a complicated concept, so be sure to watch the following video created to help visualize axial parallelism.