Exoplanet Excursions: July 2014

Jon travels to a planet where the mountains are capped not with snow, but diamonds.

The astonishing alien splendour of the Upsilon Andromedae system enthralled the senses – it seems fitting that the first multi-planetary system around a main sequence star discovered by humans should be such a spectacular one.

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Credit: Illustration by Mark Garlick

This seems to have given me a thirst for firsts, and so this time I’m on the way to the first ‘super Earth’ discovered around a main sequence star, a planet named 55 Cancri e.

I remember that during the first Sky at Night  ‘Moore Marathon’ Pete Lawrence talked about the 55 Cancri system with a particularly arched eyebrow reminiscent of Roger Moore, as if to highlight its particular fascination. If Pete says it’s good I believe him, so as Patrick Troughton’s Doctor Who would say: “Ready? Hold tight, here we go.”

55 Cancri is itself a binary star, its components widely separated. As I close in on the planetary system around the main star, a yellow dwarf, its red dwarf companion disappears from view.

The innermost planet, designated 55 Cancri e, is a remarkable tidally locked ‘super-Earth’ that is 7.8 times the mass of our planet and takes just 18 hours to complete its orbit.

This isn’t the most exciting thing about it, however: 55 Cancri e is a carbon planet. You can almost sense the force of its gravity punching through space like a Frank Bruno right cross. Being a carbon world there’s likely to be a core of iron or steel beneath the vast regions of graphite across the surface. This far-flung super-Earth could provide a permanent supply of pencils to the entire Galaxy.

Having barely had the chance to adjust the Cruiser Globe for the effects of the increased gravity, I witness a blistering volcanic eruption. Since this is a carbon planet, it’s surely got to be one of the most fascinating and profound sights the Universe can serve up – it’s raining diamonds!

Such eruptions are fairly common here and the landscapes they give rise to are glorious. The vast, glittering, mountainous regions of diamond are incredible. You can imagine this place being the destination of endless  interstellar WAG shopping voyages in future decades.

I steer the Cruiser Globe to the precise point where a sliver of the yellow dwarf star is visible beyond the planet’s horizon. Here, as the starlight cuts through the mountains of translucent diamond, they glow as if lit by candlelight. Spectacularly, these diamond mountains act like a Himalaya-scale prism, beaming the light of the home star upward into a mesmerising and permanent rainbow. This vision – the spectrum of an alien rainbow stretched over diamond mountains that are washed through with the glow of an alien dawn – is one that would inspire a flow of poetry.

All that’s missing is a soundtrack from a rather large pipe organ. In fact no, not a pipe organ. I wouldn’t be surprised if a vision like this was in the imagination of Sibelius himself as he composed At The Castle Gate.


Jon Culshaw is a comedian, impressionist and guest on The Sky at Night

This column appeared in the July 2014 issue of BBC Sky at Night Magazine

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