Standing atop a huge mound of black, hydrocarbon sand, your sandboard tucked under your arm, you take in the view. Row after row of black dunes march into the distance as far as the eye can see, until everything disappears behind an orange curtain of smog.
This is no Earthly vista: you're on Saturn's largest moon, Titan. You strap your feet onto the board and slip off down the dune. Titan's low gravity means it takes a while to build up speed, but also keeps friction to a minimum, so it's a long glide down before you come to a halt.
Sandboarding on Titan still, sadly, only happens in our imagination, but the moon's amazing dunes are real – and lie in a trippy landscape worthy of a late Beatles song. They were discovered in 2006 in radar images from NASA's Cassini spacecraft (see photo) and could be key to unravelling the climatic history of this eerily Earth-like moon.
Though chilling at -179 °C, Titan has rain and lakes – albeit of liquid methane rather than water – along with mountains and river channels.
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