An unusual astronomical phenomenon is going to take place on May 9: Mercury will pass against the Sun disk, NASA reports.

      It should be noted that the planet of Mercury, which is closest to the Sun, can be seen from the Earth only when passing between the Sun and the Earth that happens at the beginning of May or November. November passing happens more often than that of May, but it is hardly visible from the Northern hemisphere.

      The expected passing of Mercury against the Sun disk on the Victory Day can be observed in the western and central regions of Russia. However it is possible to look at the phenomenon only by means of special devices. Sun-protection filters are most required on all such devices to protect eye sight.

      Besides, the phenomenon will be broadcast online on the NASA website.