Two public lectures are provided, one on the risk to Earth posed by comet and asteroid impacts with our planet, the other a review of efforts during the eighteenth century to measure the size of our solar system and the role played by very rare planetary transits across the face of our Sun. The next Transit of Venus, the last for more than a hundred years, will be visible from Europe on 6th June this year. The free public lectures took place in the Rotunda Theatre, St. Patrick's Trian, Armagh. See more