Jupiter reaches equinox on 2 May 2021, a position where the geometric centre of the Sun’s disc appears to cross the equatorial plane of the planet. Advertisement Compared to Earth, Jupiter’s axial tilt is quite small; 3.3˚ compared to our planet’s 23.4˚. For this reason, seasonal variations on Jupiter are relatively minor. Of more significance from our perspective, the four Galilean moons Io, Europa, Ganymede and Callisto, have orbits only slightly inclined to Jupiter’s equatorial plane. A south-up telescopic view at 04:48 BST (03:48 UT) on 14 May will show the first of two of the month’s eclipses by Ganymede of Io; the second occurs on 29 May. Credit: Pete Lawrence