The South African Agency for Science and Technology Advancement is joining other organisations to enable South African citizens to witness the transit of Mercury on Monday, 11 November 2019 from 15:30 to 18:00 at the Johannesburg Observatory.

On the afternoon of 11 November, the position of planet Mercury will be directly between the Sun and Earth. Observers all over Africa will be able to see a tiny black dot making its way across the solar disk. The last time Mercury transited the Sun was in May 2016 and it will not happen for another 13 years.

The South African Agency for Science and Technology Advancement, Science Communications Manager Mr Michael Ellis, says it does not happen every day. “In fact, it will only happen again in 2032. So get ready to view the planet Mercury as it transits across the Sun – passing directly between the Sun and the Earth.  It’s almost like a bird or an aeroplane flying across the sky and directly between you and the Sun, it’s only that Mercury is much further away.”

He added that “scientists are excited about the transit of Mercury because there are various experiments they can do and observations they can make as Mercury makes its journey across the path of the Sun. Previously, scientists have made some interesting observations about the atmospheric composition of planets as the Sun’s light shines brightly through their atmosphere. Scientists have also made observations of the long term changes in the size of the Sun, by measuring what is known as the solar radius.”

As Mercury and Venus lie within the orbit of the Earth, they sometimes come exactly between the earth 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 the earth than the Moon, and appear to be smaller in the sky than the Moon.