The Chris Cross at the Fleurs field station, 40km west of Sydney, was used to generate two-dimensional high-resolution radio images of the Sun at 1420 MHz, with an angular resoltuion of 1.5 arcminutes. The figure above shows images made between the 1st and 9th of September 1958 when Sun was (as it is now) near the maximum of the 11-year solar cycle. The Sun rotates with a period of about 25 days (with the value increasing slightly with solar latitude). This is evident in the images above with the two bright spots moving from the Sun’s meridian in the first image to have rotated out of view by the 8th of September, as new spots start making their way across the Sun’s disk. (Image credit: CSIRO Radio Astronomy Image Archive )