Mercury’s Transit: Unusual Spot on the Sun
The dot is the result of an unusual type of solar eclipse. Usually it is the Earth’s Moon that eclipses the Sun. On November 14th of 2006, however, for the first time in over three years, the planet Mercury took a turn.
Like the approach to New Moon before a solar eclipse, the phase of Mercury became a continually thinner crescent as the planet progressed toward an alignment with the Sun. Eventually the phase of Mercury dropped to zero and the dark spot of Mercury crossed our parent star.
Credit & Copyright: APOD, David Cortner