Kepler’s second law states that the radius vector describes equal areas in equal times. In other words, for a circular orbit the motion of the planet is uniform, but in order for an object along an elliptical orbit to sweep out the areas at a uniform rate, the object moves quickly when the radius vector is short and the object moves slowly when the radius vector is long.

More simply stated: planets sweep out equal areas in equal times and move fastest when closest to the focus of the orbit.

Therefore when a planet is at it furthest point (aphelion) it is also moving slowest. When it is at its closest point (perihelion) it is moving fastest. The velocity of the object in orbit is constantly changing depending upon the eccentricity of the orbit. The more circular the object, the more regular the speed variations. The more eccentric the orbit the greater the change in angular momentum from closest to farthest point.

Traditionally the seasons were marked out as the planet runs through its yearly orbit around the sun. The seasons were on a continual cycle that reflects, the recognition of this psyco-energic shift. The axial tilt causes one half of the Earth and then the other to point more directly toward the sun. This is the reason that the day to night ratio is constantly changing from the longest day on the summer solstice (June 21st) to the shortest on the winter solstice - December 21st. It seems logical that dividing the year into two equal parts (four if we include the vernal and autumnal equinoxes) is the best means to account for seasonal phenomena and the affects associated with them.

The length of the day obviously influences the processes on our planet. However there is also another process which strongly influences the yearly cycle. It is the fact that the Earth’s orbit around the Sun is asymmetrical. This observation was first made in the fifteenth century by the astronomer Johannes Kepler (right) who stated in his first law that planets move in ellipses with the Sun at one focus. Circular orbits are a special case where both foci are in the same place. (Such perfectly circular orbits are almost non-existent in nature)

23.5 degree tilt of the earth.

It is well known that the seasons are due to the 23.5 degree tilt of the earth on its axis. This accounts for the most obvious feature of the year; that days and nights are longer and shorter depending on the season.





But this is not the only thing which distinguishes the year and the seasons