Galactic variations

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Climate Influences from Beyond the Solar System Last Updated on 2010-11-09 00:00:00 The Earth’s climate isn’t just a product of what’s going on within its own atmosphere. Fluctuations in climate are also determined by forcing factors (causes) external to the climate system itself. One such cause is the variation in energy from throughout the galaxy that reaches the Earth.   Relative cosmic ray flux and tropical temperature changes over time in millions of years ago (Ma). Reconstruction of cosmic ray flux is based on iron meteorite record, and that of temperature changes is based on oxygen isotope ratios d18O. Blue band indicates the error range of the cosmic ray flux. After Shaviv and Veizer 2003.   Our sun lies in the Milky Way, a swirling spiral galaxy of 200 billion to 400 billion stars. Every 150 million to 350 million years, our solar system rotates around the Milky Way. The quantity and quality of energy... More »
Milankovitch cycles Last Updated on 2010-07-07 16:09:56 Milankovitch cycles refer to long term variations in the orbit of the Earth which result in changes in climate over periods hundred of thousands of years and are related to ice age cycles. Once Isaac Newton described his laws of motion and of gravity, the orbit of each planet became predictable, not only under the influence the Sun, but the much weaker influences of all the other planets and the Moon as well. Milutin Milankovitch did not discover the cycles, nor was he the first to calculate their changes. He did, though, improve on the methods of calculating them and relating them to Earth’s climatic variations. Here is a brief description of the three cycles. Precession (also called Precession of the Equinoxes): the gravitational pull of the Sun and Moon on Earth’s equatorial bulge causes the poles to slowly wobble. Over 25,800 years, the polar axis... More »