When the first signs of life started to develop on our planet four billion years ago, the sun was only 70 per cent as bright as it is today.
Ngenkathi umhlaba wakheka cishe eminyakeni eyizigidi eziyizinkulungwane ezingama-4.600 edlule, iLanga likhiphe ukukhanya okulingana no-70% walokho elikwenzayo namuhla.