NASA’s Juno orbiter normally focuses on Jupiter’s turbulent atmosphere as it swings around the giant planet, but in this mesmerising view the spacecraft caught the tortured moon Io, the most volcanically active body in the solar system, rising above the planet’s vast horizon. Slightly larger than Earth Moon, Io is dwarfed by Jupiter’s titanic disc. This colour-enhanced image was captured by the JunoCam instrument on 29 October as June flew through its 16th close encounter with Jupiter, passing about 18,400 kilometres (11.400 miles) above the planet’s cloud tops. The image was processed by citizen scientists Gerald Eichstädt and Justin Cowart.
As it orbits Jupiter, the icy surface of Europa heaves and falls with the changing pull of its parent planet’s gravity, creating enough heat to likely support a global ocean beneath the Jovian moon’s solid shell. Experiments by geoscientists suggest that this process, called tidal dissipation, could create far more heat in Europa’s ice than scientists had previously assumed.
Early risers will already be aware that there’s currently a lot of planetary activity in the morning sky, but at dawn in Western Europe on Monday, 2 April, Mars and Saturn will be just 1¼ degrees apart and seen in the same field of view of telescopes at 30x magnification. The waning Moon is close by on the mornings of 7 & 8 April too.
Set your alarm for 6am GMT if you wish to see three naked-eye planets in the UK dawn sky this week. Find a location that offers an unobstructed view of the horizon from southeast to south and let the waning Moon be your guide to locating Jupiter, Mars and Saturn on successive mornings from 7 to 11 February.