The following daysJune 5 and 6a very rare astronomical event will take place: from Earth it will be possible to observe how Venus crosses in front of the Sun. Scientists and amateur astronomers from all over the world are already preparing to observe this rare phenomenon. After all, the last transit was in June 2004, andwill not be repeated until the year 2117.
This transit will also be thefirst in history in which there is a satellite in orbitaround our “twin” planet, the probeVenus Expressof the European Space Agency (ESA). ESA will broadcast the transit live from the arctic island of Spitsbergen, in the Svalbard archipelago, Norway, under the “midnight sun”.
The transits of Venus have great historical significance, as they were unot from the methods used by astronomers to determine the size of our Solar System. In the 18th century, astronomers were able to calculate the distance from the Earth to the Sun by measuring the time it took for Venus to cross the solar disk, taking measurements from different points on the planet, and applying simple trigonometric relationships. In the 1761 transit, a halo of light could be observed bordering the dark outline of the planet, the first proof that Venus has an atmosphere.
Currently, transits continue to be a very useful tool to test new techniques developed todetect and characterize planets orbiting other stars, outside our Solar System, known as exoplanets. When a planet passes in front of a star, it blocks a small fraction of its light, revealing its presence and giving data on its size. The European CoRot space telescope has used this technique to discover more than 20 exoplanets. Transits are also studied to search for planets that could support life. If an exoplanet has an atmosphere, a small portion of the star’s light will pass through this gaseous layer, revealing its properties, such as the water or methane content.
During next month’s transit, astronomers will have the opportunity to test these techniques and collect new data that will be incorporated into the archive of the six transits of Venus observed since the invention of the telescope in the early 17th century.
The 2012 transit can be seen entirely from the Western Pacific, East Asia, and eastern Australia, as well as from high northern latitudes. For the United States, the transit will begin on June 5 in the afternoon and, for most of Europe, the sun will rise on the 6th when the transit is coming to an end. The sun never setsSpitsbergenduring the month of June, which offers an exceptional opportunity toobserve the complete transit from European territory. It will start at 22:04 GMT on June 5 (12:04 CEST on June 6) and will end at 04:52 GMT (06:52 CEST). The scientists from ESA’s Venus Express project will travel there.
