Among all the astronomical ephemeris of this year, the transit of Mercury is, without a doubt, one of the most outstanding. And it is that planetary transits happen infrequently. Only Mercury and Venus give rise to this type of phenomenon , since they are the planets that at some point during their orbit around the Sun come between it and the Earth.
Due to Mercury’s closer proximity to the Sun, its transits occur more frequently . In the case of Venus, the frequency is lower. The last transit of Mercury took place in 2006 and there will not be another one until 2019. In the case of Venus, the last transit happened in 2012 and there will not be another until the year 2117.
The first recorded transit of Mercury occurred in 1631 . The astronomer Pierre Gassendi, taking advantage of the predictions of planetary positions made by Johannes Kepler a few years earlier, was able to record the phenomenon thanks to the use of a rudimentary telescope. For several centuries, this phenomenon has been exploited to improve calculations of the size of the Solar System and also to increase the precision of calculations of the units of measurement used in astronomy to compute distances.
The transit of Mercury this year can be seen from Europe . It will begin at approximately noon and it will take the planet a little over seven hours to cross the solar disk. To observe this phenomenon, it will be necessary to use a telescope equipped with a solar filter . You should never observe the Sun directly through a telescope without a solar filter, as the damage to your eyesight is irreparable. Depending on the solar activity of the month of May, with a bit of luck, it may be possible to observe how the planet hides some sunspots, although this will not be known until shortly before the event.
In addition to observing the traffic, it is possible to take photographs of the event, or even record it on video . To do this, it is necessary to attach the camera to the telescope, using the corresponding adapters . In this way, the telescope replaces the photographic objective. In this case the solar filter must also be installed on the telescope, otherwise the camera sensor will be damaged. On this occasion, and if the weather permits, we will have the chance to enjoy this astronomical show that will not be repeated for another three years.
Amadeo Aznar, Isaac Aznar Observatory, CAAT-Alto Turia Astronomical Center.
