Exoplanet Excursions: February 2015

Jon tracks down another alien eclipse – this time involving a mighty gas giant

As 20 March approaches I find myself thinking more and more about pristine, clear skies for nature’s most spectacular sight, the total solar eclipse that will be visible from the Faroe Islands.

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Image Credit: 
Mark Garlick
Credit: Illustration by Mark Garlick

I vividly remember the eclipse of 11 August 1999, seen from a ferry on the English Channel. There were sufficient cloud gaps to fuel optimism about a spectacular view. BBC weather presenters gave commentary over the Tannoy about where the ship was steering to find gaps in the clouds, while Uri Geller moved among the passengers talking about ‘The Energies’.

I’ll never forget the strange, steel-grey twilight that enveloped us shortly before totality: a unique, monochrome dusk with a weird silvery glow, which only impending totality could create. As Patrick Moore might say, “It was frankly... eerie.”

So, keeping our visions profound on these excursions, I’m going to see a red giant star eclipsed by a great gas giant. My destination is HD 208527, a red giant that lies some 1,044 lightyears from Earth in the constellation of Pegasus. The gas giant orbiting it bears the name HD 208527b, but I’m going to name it ‘Jupideci’ – after all, it does have a mass of around 10 times that of Jupiter.

Jupideci sits 2.1AU away from its parent star – quite possibly nestled within its habitable zone – and takes about 876 days to complete an orbit. Any Moons orbiting this world may well possess liquid water and the possibility of life. The redness of the star itself is reminiscent of observing our Sun in hydrogen-alpha.

As the dark disc of Jupideci advances to obscure its parent red giant, my anticipation of witnessing an alien eclipse is beyond palpable. In the moments leading to exo-totality, the thinnest crescent with a smouldering ochre glow pulsates against the solid blackness of space. The red giant eclipse hangs in this alien skyscape like a sickle freshly removed from a blacksmith’s forge. Sensing the scale of the objects involved, totality arrives with the surety of a massive ocean vessel steadfastly occupying its place in dock.

The sight is utterly magnificent. Unlike solar eclipses visible from Earth, which have a solid black inner outline, the black disc here has a softer, blurry edge. The outer layers of the gas giant allow a little of the red giant’s light to shimmer through. It’s a charming nuance of this eclipse.

The blackness of the Jupideci disc is surrounded by a halo glowing the deepest orange shade of volcanic magma. It’s similar to our Sun’s corona but with a softer, less filamented structure. It brings a sense of being bathed in the cosy glow of a Victorian fireplace on a cosmic scale. If the Cruise Globe’s robotic arms were able to stretch out far enough, I’d be tempted to stick a slice of bread on the end for some space toast.


Jon Culshaw is a comedian, impressionist and guest on The Sky at Night
This column appeared in the February 2015 issue of BBC Sky at Night Magazine
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