Mercury Transit

This image shows a rare transit of Mercury, where the tiny dark dot of Mercury passes directly in front of the bright disk of the Sun as seen from Earth.

A Transit of Mercury occurs when the planet Mercury passes directly between the Earth and the Sun, appearing as a tiny black dot moving slowly across the Sun’s bright disk. Because Mercury’s orbit lies inside Earth’s orbit, only Mercury and Venus can produce such transits, and they happen only when Mercury’s orbital path crosses the Sun from our point of view. Even though Mercury comes between Earth and the Sun several times a year, its orbit is tilted by about seven degrees, so most of the time it passes above or below the Sun. Only when everything lines up perfectly does a transit occur, making these events rare and exciting to watch through properly filtered solar telescopes.