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Why Ice Ages Happen

Ice ages may occur when our Solar System passes through thespiral arms of the Milky Way during our orbit around thecenter of the galaxy. Dr. Nir Shaviv of the University ofToronto has found evidence linking changes in the cosmicrays reaching the Earth and the times that ice ages occurredin the past.

He believes that the cosmic rays come from stars thatexplode as the Earth exits one of the Milky Way's spiralarms. The increased cosmic rays then trigger ice ages on Earth.If this is true, we won?t have another ice age for tens ofmillions of years, since our Solar System is not due toleave another spiral arm for a very long time.

Spiral arms are not permanent features of the Milky Way.They?re formed by ?density waves? that travel around thegalaxy every 500 million years or so. Many short-lived starsare born in these waves, and these explode within a millionyears and turn into supernovas. Shaviv thinks thesesupernovas are a major source of cosmic rays.

Shaviv estimated the times when the Earth was exposed tocosmic rays by looking at how cosmic rays effected 30meteorites that were in orbit for long periods during thepast billion years before they fell to Earth. Detailedanalysis of the cosmic ray tracks in the meteorites showedthat the intensity of cosmic rays striking our Solar Systemvaries and these variations are in synch with ice ages hereon Earth.

This may explain why dinosaurs were declining before theywere wiped out by a meteor impact 67 million years ago.About 70 million years ago our Solar System entered theSagittarius-Carina spiral arm, which would have caused areduction in the Earth's temperature. It was not enough tostart a new ice age, but it was enough to start thedinosaurs? demise.

Whoever is making the crop circles is trying to tell ussomething. To take a look at the latest messages from thebeyond,click here.

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