The challenge
The awakening, for me, came the morning of June 10, 2020, when I trained a pair of 8x42 binoculars on Jupiter at 4:21 UT from Maun, Botswana, shortly after the start of astronomical twilight. A waning gibbous Moon was nearby, which also helped illuminate the background sky and cut down on contrast. With a glance, I saw three moons. And had I put down the binoculars, I would have left it at that — assuming that the fourth moon was either behind or in front of the planet, or very close to its edges.
But as I fiddled with the focus, I suddenly saw the moon closest to Jupiter take on an egg-shaped appearance. When I braced the binoculars against the hood of my car, I resolved the “egg” into two close moons.
On July 4, 2020 at 18:47 UT, I used the same binoculars to observe Jupiter. This time, a prolonged study revealed two moons, Ganymede and Callisto, on opposite sides of the planet. I then used a telephoto lens to image Jupiter. To my surprise, the image showed another moon (Europa) only about 16" east of Jupiter’s disk; Io was occulted by the planet.
Try as I might, I could not see Europa through the 8x42s, nor in 10x40s. The moon was, however, just visible through 10x50s, though both stabilized binoculars and patience were required to pull it out from the planet’s glare.
Two weeks later, on July 18 (18:00 UT), three moons were visible (Callisto, Europa, and Ganymede) through 8x42 binoculars. Europa, however, was only seen with difficulty, even though it was roughly one Jupiter diameter (47.5") to the west of the planet. I found this the most surprising sighting of all, as I had expected that moon to be clearly visible at this apparent separation.