📅 7 November 1631
Pierre Gassendi observed Mercury as a tiny dark dot moving across the solar disk.
📅 7 November 1631
The observation provided a direct test of a calculated planetary transit.
📅 7 November 1631
The apparent size of Mercury on the Sun surprised observers and helped refine ideas about its dimensions.
📅 7 November 1631
The 1631 Mercury transit showed how a projected solar image could support planetary measurements.
