I have been undertaking some research for some upcoming seminars I will be conduction on Sustainability, Climate Change and the NZETS.
I must have missed that class at college about the Milankovitch cycles so I thought that the reads of this BLOG may also be interested too??
Milankovich Cycles

The Milankovich cycles refers to changes in the earth’s orbit and orientation toward the sun and have long term important bearings on the earth’s climate.
Astronomer Milutin Milankovitch [1879 – 1958] developed the mathematical formulas upon which these orbital variations are based. He hypothesized that when some parts of the cyclic variations are combined and occur at the same time, they are responsible for major changes to the earth's climate (even ice ages). Milankovitch estimated climatic fluctuations over the last 450,000 years and described cold and warm periods.
The Serbian astrophysicist Milutin Milankovitch is best known for developing one of the most significant theories relating Earth motions and long-term climate change. Born in 1879 in the rural village of Dalj (then part of the Austro-Hungarian Empire, today located in Croatia), Milankovitch attended the Vienna Institute of Technology and graduated in 1904 with a doctorate in technical sciences. After a brief stint as the chief engineer for a construction company, he accepted a faculty position in applied mathematics at the University of Belgrade in 1909—a position he held for the remainder of his life.
You may have missed this science class at school and may not be aware that the axis of the earth pointing toward the North Star (Polaris) is at an angle of 23.45° and that the earth is approximately 91-94 million miles from the sun, these facts are not absolute or constant. The interaction between the earth and sun, known as orbital variation, changes and has changed throughout the 4.6 billion year history of our planet.
Orbit Variations
About every 100,000 years the earth’s orbit around the sun varies from nearly circular to elliptical (elongated). This has an effect on the amount of the suns radiation that strikes the earth. When circular the variations are around 6% between summer and winter. However in an elliptical phase the variation can be 20-30%!
You may think that most objects in space that orbit something else move in circles, but that isn't the case. Although some objects follow circular orbits, most orbits are shaped more like "stretched out" circles or ovals. Mathematicians and astronomers call this oval shape an ellipse.
The eccentricity of Earth's orbit is very small, so Earth's orbit is nearly circular. Earth's orbital eccentricity is less than 0.02. The orbit of Pluto is the most eccentric of any planet in our Solar System. Pluto's orbital eccentricity is almost 0.25.
The Sun is not at the center of an elliptical orbit. It is a little off to one side, at a point called a "focus" of the ellipse. Because of this offset the planet moves closer to and further away from the Sun every orbit. The close point in each orbit is called perihelion. The far away point is called aphelion. If an orbit has a large eccentricity, the difference between the perihelion distance and the aphelion distance will also be large. Earth is only 3% further from the Sun at aphelion than it is at perihelion. Pluto's aphelion distance from the Sun is 66% greater than its perihelion distance.
Axis Tilt

About every 42,000 years the tilt of the earth’s axis ranges from 21.8 to 24.4 degrees. This tilt determines the angle of solar radiation that hits the earth’s surface. At present we are around 23.5 degrees.
The Earth's axis is tilted from perpendicular to the plane of the ecliptic by 23.45°. This tilting is what gives us the four seasons of the year - spring, summer, autumn (fall) and winter. Since the axis is tilted, different parts of the globe are oriented towards the Sun at different times of the year.
Summer is warmer than winter (in each hemisphere) because the Sun's rays hit the Earth at a more direct angle during summer than during winter and also because the days are much longer than the nights during the summer. During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short. These effects are due to the tilt of the Earth's axis.
Orientation
About every 22,000 years the orientation of the earth’s axis changes between the Pole star and the Vega star. This determines what time summer and winter occurs!
The term "Earth orientation" refers to the direction in space of axes which have been defined on the Earth. It is usually measured using five quantities: two angles which identify the direction of the Earth's rotation axis within the Earth, an angle describing the rotational motion of the Earth, and two angles which characterize the direction of the Earth's rotation axis in space. With these coordinates, the orientation of the Earth in space is fully described.

Pole Star
A pole star is a visible star, especially a prominent one that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent position is close to one of the celestial poles, and which lies (approximately) directly overhead when viewed from the Earth's North Pole or South Pole. There are potentially both northern and southern pole stars, but whether there is either depends on the current orientation of the Earth's axis, which moves over time (see precession of the equinoxes). The term the Pole Star usually refers to the star Polaris (colloquially referred to as the North Star), which is the current northern pole star.
