MESSENGER, an artist's impression

ESA’s Venus Express, in orbit around Venus since 11 April 2006, will be joined for a few hours by NASA’s MESSENGER spacecraft, flying by Venus while on its way to Mercury.

Earth-based observatories and telescopes in orbit around Earth will also be watching. Looking at Venus together, spacecraft and ground observatories will obtain a unique set of data each, so many different ‘eyes’ will observe the same regions and phenomena during the same time frame.