Mercury crossed the disc of the Sun on 1970 May 9th. The map above shows the visibility of the transit.
The geocentric circumstances of the transit are shown in the diagram to the right. During the transit, the diameter of the Sun was 1901.0 arcseconds and that of Mercury was 12.1 arcseconds. In other words, the diameter of Mercury was 0.006 that of the Sun, making it look like a very small, rapidly moving sunspot. The whole transit lasted just under eight hours.
The minimum separation between the centre of the solar disc and Mercury was 114.1 arcseconds.
HM Nautical Almanac Office
UK Hydrographic Office
Last revision was made on 2007 November 5