For the first time since 9 May 2016, Africans will be able to watch Mercury transit the Sun on Monday, 11 November at 14:35 Central Africa Time (CAT). People with access to telescopes are encouraged to take the opportunity to view this rare event, as those who miss out will have to wait until 13 November 2032 for the opportunity to do so again.
The Department of Science and Innovation (DSI) will host a viewing event which will include a short talk on this astronomical phenomenon. Takalani Charles, Junior Astronomy Policy Researcher at the DSI and Interim Administrative Officer at the African Astronomical Society, will explain what transits are and why they occur.
When it comes between the Sun and the Earth on Monday, the planet Mercury will appear as a small black dot moving across the face of the Sun (unlike a solar eclipse, when the Moon wholly or partially covers the Sun).
The transit will be observable from anywhere in Africa by projecting the image of the Sun through a small telescope. Observers are warned not to look at the Sun directly, even for a second, whether through a telescope or binoculars or with the naked eye, as this could cause permanent damage to your eyes. However, if you project the image of the Sun onto a piece of paper, it is perfectly safe to look at the projected image. In this way, you can also show the transit to many people simultaneously.
How much of the transit you will be able to see will depend on when the Sun sets at your location, which will be later for more westerly regions. For example, while the Sun will set at 18:31 for Johannesburg, it will only set at 19:33 for Cape Town.
As Mercury and Venus lie within the orbit of the Earth, they sometimes come exactly between us and the Sun, and can be seen crossing the face of the Sun for the duration of a few hours. These planets are much farther away from us than the Moon, and therefore appear to be much smaller in the sky than the Moon. Because of these planets’ size relative to the Sun, a transit can only be seen by means of a telescope.
Source: Department: Science and Technology