Spotting a comet in the all-sky maps from SOHO's instrument SWAN
An animation showing the movement of comet C/2020 F8 (SWAN) through successive all-sky maps made by the Solar Wind ANisotropies (SWAN) instrument aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO). The sequence covers the period from 1 April to 9 May 2020. The comet can be seen as a moving white blob on the left of the image, just below the middle line of the coordinate grid, indicated with an arrow starting from the 5 April map. The comet is small to start with but gradually grows bigger. It was using these maps that Australian amateur Michael Mattiazzo discovered the comet.
Between 17 and 27 April, the comet disappears behind the black areas that identify regions of the sky too bright to be observed, but by 28 April it is clearly visible again towards the left edge of the map. When the comet leaves the left-hand side of the image, it reappears on the right-hand side after 2 May (the image represents the 360-degree sky mapping used by SWAN).