Earth's Rotation

         Here's an interesting scientific question I pondered for a while (and now have an answer to): How many times does the earth rotate in one year? At first, it would seem the answer is a simple "365," corresponding to the number of days in one year. However, let me explain why this can't be so.

         Think about it this way: if the world didn't rotate at all, in the course of one full revolution around the sun we'd already have a full cycle of day and night every year. Imagine looking at the process First Animation - 114 KB from above (if you have a bad imagination, click on the picture to the right for an illustrative animated picture): when the earth was to the right of the sun, daylight would be on the left side of the earth. As the earth revolved counter-clockwise to above the sun, the bottom of earth would be getting sunlight, though not the left. The left side of the earth wouldn't get light again until earth moved back to the right of the sun, thus forming one full day/night period.

         If that's so, then to get to 365 days a year (which is what we have, give or take a fraction), Second Animation - 114 KB we'd only need 364 rotations a year!!! (Click to the left to see this second scenario - one more day than rotation - in action, on a smaller scale, with one rotation and two days.) Well, that may not be entirely true. If the earth rotates Third Animation - 132 KB in the same direction as its revolution, that would be true. However, and about this I am unsure, the earth may rotate counter to the direction of its revolution, in which case if it rotated once a year, that one rotation would counteract the day "created" by the revolution, resulting in 0 days. (Click to the right for a third visual aid.) Two rotations would result in one day, three rotations - two days, etc. In order to get to 365 days, we'd need 366 rotations.

         I now have an answer to this question. If you're interested, please continue on.

         A note about the animations: I know they're not to scale, but that's not the point. I created the animations using POV-Ray, a ray-tracing program. To find out more about it, check out the POV-Ray site. To find out more about how I made these particular animations (i.e., to see the POV-Ray code for them), e-mail me.