From M.G. Harman
On pages 30 and 31 of the 21 January issue (“Day of the comet”) there is a picture of Jupiter from “behind”, with the Sun almost grazing the edge of Jupiter’s disc. Jupiter is mostly dark and the background is of course black.
Reading the adjacent text about 250 millimetres away, I realised that the sun was blazing brilliantly to the side – far brighter than the white of the paper. Looking straight at the sun, it appears somewhat brighter than the white of the paper round the picture, but not nearly to the same degree.
It’s quite startling, isn’t it? The effect – of white appearing brighter against a dark background – is in fact a classic optical illusion – Ed
