|Transits of Venus: 1000AD–2700AD|
|1032 May 24||1040 May 22|
|1145 November 26 †||1153 November 23-24||1275 May 25-26||1283 May 23|
|1388 November 26 †||1396 November 23||1518 May 25-26||1526 May 23|
|1631 December 7||1639 December 4||1761 June 6||1769 June 3-4|
|1874 December 9||1882 December 6||2004 June 8||2012 June 5-6|
|2117 December 11||2125 December 8||2247 June 11||2255 June 9|
|2360 December 12-13||2368 December 10||2490 June 12||2498 June 10|
|2603 December 15-16||2611 December 13|
The second transit of the 19th century again stimulated considerable efforts by astronomers from countries worldwide. However, some astronomers did not take part in the international collaboration, most notably Russia and Austria, because they were not convinced that the transit was the best way to determine the solar parallax. Astronomers from the United States went on eight expeditions including Asaph Hall to San Antonio and Simon Newcomb to Wellington in South Africa. British observers went to Southern Africa, Australia, Canada and the Caribbean. French observers mounted ten expeditions ranging from Fort Marion in Florida to Cape Horn and from Puebla in Mexico to Fort Tartenson in Martinique. In 1890, Newcomb determined a value for the solar parallax of 8.79 arcseconds from observations made in 1874 and 1882 which compares very favourably to current best estimates.
Venus crossed the disc of the Sun on 1882 December 6th. The map above shows the visibility of the event. The entire transit was visible from South and Central America as well as the eastern half of North America. The Sun set during the transit in the grey area encompassing Africa and Europe including the British Isles. The Sun rose while the transit was in progress in the grey area taking in northern and western parts of North America, the Pacific Ocean and eastern Australia. The yellow lines on the diagram show the position of the terminator, where the Sun is either rising or setting, at the key phases of the transit.
The geocentric circumstances of the transit are shown in the diagram above. During the transit, the diameter of the Sun was 1946.6 arcseconds and that of Venus was 63.1 arcseconds. In other words, the diameter of Venus was 0.03 that of the Sun, making it look like a rapidly moving sunspot. The whole transit lasts just over six and a quarter hours.
All timings are given in Universal time (UT).
Local time in South Africa is 2 hours ahead of Universal Time.
In Wellington, the transit began with exterior ingress at 13h52m (UT). Venus took 20 minutes to cross the limb of the Sun with interior ingress at 14h12m (UT). Venus reached its minimum separation of 630.0 arcseconds from the centre of the solar disc at 17h02m (UT). Interior egress occurred at 19h54m (UT). Venus took 20 minutes to cross the limb of the Sun for the second time with exterior egress occurring at 20h14m (UT).
The progress of the transit is summarized in the diagram below. The left-hand panel shows the movement of the Venus across the solar disc. The top of the diagram points to the zenith, the point directly overhead. The position of Venus is marked every UT hour. The right-hand panel shows the movement of the Sun in the sky. At the beginning of the transit, the Sun was in the west at an altitude of 66°. By the time of minimum separation, the Sun was in the south west at an altitude of 7°. Sunset occurred at 17h44m (UT).
Summary plots like the one shown above and animations showing the motion of Venus relative to the Sun as seen by someone observing the transit through appropriate eye protection are available for several locations worldwide. The summary gif files are ~18Kb and the animations are ~200Kb. To view the animations properly, it may be better to download the animations and view them locally.
|Local Circumstances of the 1882 Transit|
|Location||Sunrise (UT)||Sunset (UT)||Downloadable gifs|
|Wellington, South Africa||03h27m||17h44m||Animation||Summary|
|San Antonio, United States||13h15m||23h35m||Animation||Summary|
|Punta Arenas, Chile||08h13m||00h58m||Animation||Summary|