This portrait of the Earth and Moon together in space was taken on 26 August by NASA’s Juno spacecraft which is currently en route for Jupiter. The image was made when Juno was about 10 million km away as part of the checking procedure for the probe’s instruments.
If you rise from Earth you’ll have to cross about 380 000 km before you reach the Moon. Rays of sunlight sparkling off the Earth’s oceans race across this distance in a mere 1.2 seconds, in contrast forty years ago Apollo spacecraft took about three days to plod between the worlds. Earth and the Moon form a “double planet” unique in the Solar System. Our moon is large in itself (being the fifth largest moon in the Solar System) but it is unusually and uniquely big compared to its primary being a little more than a quarter of the Earth’s diameter across. Almost certainly both worlds were born together when a Mars-sized world glanced off the proto-Earth some 4.5 billion years ago, smashing itself in the process. The Moon as we see it now congealed from the debris ripped from Earth and the lost world mangled in this ancient cataclysm. Looking at this serene duo it is hard to imagine that they were birthed in such violence.
This two-world portrait shot will not be Juno’s last look back home as it will return on 9 October 2013 to skim past Earth in the gravity assist manoeuver that will finally fling it towards its destination and ultimate resting place in the Jovian system.