Spying on a neighbour

gas giant uranus

In well over a decade of

planetary observations, Cassini

has never imaged the gas giant

Uranus – until now. Peering

past the visible outer rings of

Saturn, a blue spot can be seen

in the upper left-hand corner of

the image: Saturn’s other nextdoor

neighbour, Uranus. It’s

approximately 28.6 astronomical

units away from Saturn here

(4.3 billion kilometres / 2.66

billion miles) and a pale blue

colour because the methane

gas in the atmosphere allows

that wavelength of blue light to

reflect back into space.