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Posts Tagged ‘The Astronomical Unit’

In June 2012 I travelled to the Gobi Desert in Mongolia to observe the 2012 Transit of Venus, the last one until December 2117. But, my reason for wanting to see this event was not just because they are incredibly rare. It was also because of their historical importance. They provided the first reliable method astronomers had for measuring the distance from the Earth to the Sun.

Over the next several weeks I will blog the slides from a lecture I put together back in 2004 (when we also had a Transit), explaining how a Transit of Venus can be used to measure the distance from the Earth to the Sun. I also provide some of the historical background to early observations of transits, including the heroic efforts undertaken by scientists in the mid 1700s.

This is the first part of the lecture, taking us from early Geocentric models of the Solar System to Galileo’s evidence that the Sun (and not the Earth) was at the centre of the Solar System, and up to the first ever predicted Transit, which was in 1631, although as far as we know no-one observed it.



This is a lecture I gave in Mongolia the night before the June 2012 Transit of Venus, but it is based on a talk I gave to schools and the public in 2004.

This is a lecture I gave in Mongolia the night before the June 2012 Transit of Venus, but it is based on a talk I gave to schools and the public in 2004.



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