Sometimes an image comes along that takes your breath away. That is not unusual in the amazing world of astronomy but the latest offering from the Cassini probe really stands out.
It shows the unlit side of Saturn’s rings as a brilliant electric blue, while the night side glows red like an ember. The part of Saturn catching sunlight shows in sapphire and mint green.
The picture looks unreal and, in truth, the colours are false. But they were fitted to 25 images recorded by Cassini’s visual and infrared mapping spectrometer as it built up a mosaic of the ringed planet over 13 hours on February 24.
Cassini was looking down on the northern hemisphere of Saturn from a distance of 1.58 million km (a million miles). The red glow represents thermal radiation detected coming from the planet’s night side and generated deep beneath the clouds.
We have seen this red glow before when the probe caught a fascinating view of a mysterious hexagonal feature at Saturn’s north pole. And of course there have been other remarkable pictures returned of the planet and its rings. The Cassini team note that Saturn’s northern hemisphere is about twice as bright as the south where fine particles high in the atmosphere block the glow.
Photo: Nasa/JPL/University of Arizona.