Transit of Mercury
Videos
A transit of Mercury across the Sun takes place when the planet Mercury passes directly between the Sun and a superior planet. During a transit, Mercury appears as a tiny black dot moving across the S
Transit of Mercury on November 11, 2019
Transit of Mercury on November 8, 2006 with sunspots #921, 922, and 923
Transit of Mercury, 2006 11 08 2
Mercury in true color
Black drop effect
Videos
The black drop effect is an optical phenomenon visible during a transit of Venus and, to a lesser extent, a transit of Mercury.
Transit of Mercury
…Looking for long term variations in the solar radius. Investigating the black drop effect, including calling into question the purported discovery of the atmosphere of Venus during the 1761 transit. Assessing the likely drop in light level…
Venus transits the face of the Sun on 8 June 2004. Here, the black drop effect is visible.
The black drop effect as observed by Captain James Cook and Charles Green in 1771.
The black drop effect in 2004, in moments of "bad" seeing (left) and "good" seeing (right).