Elliptical Truths

clipped from www.sciencedaily.com ScienceDaily (Feb. 18, 2008) — The Earth's orbital behaviors are responsible for more than just presenting us with a leap year every four years. parameters such as planetary gravitational attractions, the Earth's elliptical orbit around the sun and the degree of tilt of our planet's axis with respect to its path around the sun, have implications for climate change and the advent of ice ages. People often think of orbits as circular, but they're not that smooth and simple. They are often a less-than-perfect eccentric circle. "All planets travel in an ellipse around the sun, but the shape of that ellipse oscillates," he explains. "When the Earth's orbit is more elliptical, the planet spends more time farther away from the sun, and the Earth gets less sunlight over the course of the year. These periods of more-elliptical orbits are separated by about 100,000 years. Ice ages occur about every 100,000 years, and they line up exactly with this change in the Earth's elliptical shape."