This stunning image of Jupiter with its Great Red Spot (GRS) shortly after transit was captured by Christopher Go in the Philippines using a Celestron C14 telescope and QHY 290M camera on 22 June 2019 at 15:44 UT. Note the turbulence in the wake (left) of the GRS and the different appearance of the planet’s main North and South Equatorial Belts. The GRS is visible in 7.6-cm (3-inch) and larger telescopes on nights of good seeing. North is up and celestial east is to the left. Image credit: Christopher Go.As June draws to a close, largest planet Jupiter is an unmistakable magnitude -2.5 naked-eye object found highest in the southern sky of the British Isles close to 11:30pm BST. By 13 July, when the planet lies close to the 11-day-old Moon, the pair attain their peak altitude due south around 10:45pm BST.
Jupiter’s current location in the southern reaches of the constellation Ophiuchus does mean that the planet gets no higher than 14 degrees above the southern horizon for an observer in the heart of the UK, but on nights of calm air with good seeing there are still wonders to behold with telescopes of apertures as small as 7.6-cm (3-inch) at magnifications of 100× or more.
Great Red Spot
While Jupiter’s Great Red Spot (GRS) appears to have temporarily ceased its flaking activity (see this story), observers should keep a keen eye on this Earth-sized anticyclonic storm in the Jovian atmosphere.
The table at the bottom of this page lists the best times to see the GRS for observers in the British Isles and those parts of Western Europe at a similar longitude (e.g., Spain, Portugal, Central and Western France). For other locations worldwide, consult our interactive online Almanac, ensuring that the ‘Add phenomena of Jupiter?’ checkbox is ticked.
Jupiter’s moons
The largest planet always has more to offer than cloud features in its constantly churning atmosphere. Jupiter is a veritable miniature solar system in its own right, with a family of 79 known natural satellites. The four large Galilean moons — Io, Europa, Ganymede and Callisto — regularly pass in front of (transit), are eclipsed (passing into shadow) or occulted (hidden) by Jupiter.Due to the current orbital inclination of Callisto to our line of sight, the outermost Galilean moon passes above or below Jupiter at conjunction. Observers in the UK can witness this (weather permitting) on Sunday, 14 July at 11:31pm BST when Callisto passes slightly less than 4 arcseconds south of Jupiter. Earlier this night, don’t miss Io (left) emerging from Jupiter’s shadow at 11:19pm BST. AN graphic by Ade Ashford.Io, Europa and Ganymede display transits, shadow transits (where their shadows appear as inky black dots drifting across Jupiter’s cloud tops), eclipses and occultations throughout July, as summarised for the British Isles and similar longitudes in the table below.Phenomena of Jupiter and its bright Galilean moons visible from the British Isles throughout July 2019. Note that all events are given in British Summer Time (BST), so subtract one hour to convert to Universal Time/GMT. Computation and data preparation: Ade Ashford/Guide.
Mighty Jupiter, the king of the planets, comes to opposition at 08:00 UT on 14 July, the moment when it lies opposite the Sun in sky at a distance of 619.4 million kilometres (384 million miles), or 4.139 astronomical units.
The continued edgewise orbital aspect of Jupiter’s large moons Io, Europa, Ganymede and Callisto means that they still regularly eclipse and occult each other. Multiple shadow transits also continue throughout January.
A team of scientists has documented atmospheric changes on Io, Jupiter’s volcanically active satellite, as the giant planet casts its shadow over the moon during daily eclipses. Io’s thin atmosphere collapses as the sulfur dioxide gas emitted from volcanoes freezes when shaded by Jupiter. The atmosphere reforms when Io moves out of eclipse and the ice sublimates.
