cropped-mars-landingThe latest blogs from the Science Geek have been about our developing understanding of the Earth’s position in the cosmos in relation to other bodies and systems.

The first, Geocentric Cosmology, was about the basis of the geocentric model which placed the Earth at the heart of things.  The second, Copernicus, is about the science that introduced heliocentric theory.  As ever, these are lucidly written with excellent diagrams which illustrate the most basic elements of an environmental education.

Here’s how the second post begins:

Background – the need for a better theory

As mentioned in my last post, the geocentric theory was the generally accepted theory of the cosmos until the early 16th century, having been developed by the second century Greek astronomer Claudius Ptolemy.  To make it fit the observations, Ptolemy needed to fine-tune his theory, making it rather complex.  Rather than moving directly around the Earth, the Sun, the Moon and the planets moved around small circles called epicycles and the centre of each epicycle moved, at a varying speed, around a larger circle called a deferent.  A further complexity was that the centre of the deferent wasn’t the Earth but a point nearby, which Ptolemy called the ‘eccentric’.  …

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