Venus as a transiting planet

Transmission spectrum of Venus as a transiting exoplanet

Useful data for distinguishing Earth-like and Venus-like terrestrial planets.

http://www.ras.org.uk/news-and-press/219-news-2012/2203-venus-transit-and-lunar-mirror-help-astronomers-find-worlds-around-other-stars

On 6 June 2012 Venus passed directly between the Earth and the Sun, in a so-called transit where the planet appears as a silhouette against the solar disk, something that will not happen again until 5 December 2117. A team of Italian astronomers led by Paolo Molaro of the Instituto Nazionale di Astrofisica at the University of Trieste used the opportunity to perform an unusual and challenging experiment, looking at the sunlight reflected off the Moon ('moonlight') to see how it changed during the transit. This technique could help scientists to find planets in orbit around other stars