There will be a rare celestial drama on May 9, when Mercury the fiery planet and the smallest in our solar system passes directly between the Sun and the Earth. This transit happened earlier in 2006 – there are approximately 13 transits of Mercury each century. The next transit will be on November 11, 2019.
Astronomers say Mercury will be seen as a small black dot crossing the surface of the Sun. They have warned, however, not to look a the sun directly and only do so with the help of proper eye protection. Severe retinal damange could take place. Mercury’s travel across the sun will take place over a period of several hours.
Since Mercury is only 1/158 of the Sun’s apparent diameter, scientists say that ideally a telescope with a magnification of 50x or more is recommended to watch this event.
The first observation of a transit of Mercury was on November 7, 1631 by Pierre Gassendi, a French philosopher and priest.
Because Mercury orbits the Sun within Earth’s orbit (as does Venus), it can appear in Earth’s sky in the morning or the evening, but not in the middle of the night. The first man-made craft to approach the planet was the Mariner 10 which flew by. Mercury was first closely studied by NASA’s “Messenger” probe, the first spacecraft to orbit Mercury, between 2008 and 2015. It made 4,000 orbits in four years, before exhausting its fuel and crashing into the planet’s surface on April 30, 2015.
Mercury will be visited again in 2024 when “BepiColombo”, a joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA), scheduled for launch in 2017, will be placed into orbit around the planet.