Exoplanet Excursions: January 2015

Jon’s eclipse-chasing desire leads him to Piscis Austrinus for an interstellar perspective.

One of the most spectacular coincidences on Earth is the very fact that total solar eclipses take place: that the Sun is both 400 times larger than the Moon and 400 times further away from us.

 

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Credit: Illustration by Mark Garlick

This wonderful fluke means that the Sun and Moon appear the same size, allowing our Moon to perfectly block the solar disc and give us the glory of totality.

I heartily agree with Sir Patrick Moore’s assertion that total solar eclipses are the most incredible sight in all nature and I’m giddy to discover how they might appear in other parts of the Universe around other stars. So I’m steering the cruiser globe to Fomalhaut, a young blue star 25 lightyears from the Sun and the brightest star in the constellation of Piscis Austrinus, the Southern Fish.

Fomalhaut is believed to be around 200 million years old and is approximately twice the mass of our Sun. This youthful star is very much faster, fiercer and more active than our middle-aged home star: the stellar equivalent of a 19-year-old knocking back high-caffeine energy drinks at Reading Festival in contrast to a more matured soul, who much prefers a quiet brew with a macaroon watching Dickinson’s Real Deal.

Orbiting this star is the gas giant Fomalhaut b, a world estimated to be two or three Jupiter masses. I’m going to settle in the region of this planet – one of the first extrasolar worlds to be imaged directly – to assess where best to observe a total Fomalhaut eclipse from. This planet is around 115 AU from Fomalhaut, rather far back to observe  the kind of eclipses familiar on Earth,
so I cruise closer into the habitable zone until I’m just 2.5 AU from the star. Here, I have the supreme fortune to locate a rocky world sized somewhere between Mars and Earth.

By steering the Cruiser Globe to a point where this rocky world appears in its ‘new’ phase, and then reversing to where it appears identically sized to Fomalhaut itself, I have an amazing chance to witness a beyond breathtaking alien eclipse. I shall name this rocky world ‘Totalis’ in honour of the exo-eclipse it’s allowing us to see.

What a majestic, eerie sight; a total stellar eclipse. Surrounding the solid black disc of the ‘new’ Totalis, the Fomalhaut corona pierces outwards with elongated, spindly rays, like the outstretched arms of someone doing a funny dance.

This corona is a distinct silvery blue and visibly fast moving, as if it’s being blown in a cosmic breeze. The shape is evocative of medieval sketches of the Sun. Prominences shimmer in pure, piercing white, very differently to the Sun’s prominences of burgundy flecks during totality seen from Earth.

At the end of the eclipse, the valleyed terrain of Totalis gives three separate diamond ring effects at the one, three and four o’clock positions. To witness another variety of total eclipse is a breathtaking exoplanetary vision. I could get the taste for this. Eclipsed red giant viewed through dazzling auroral activity on an icy exoworld, anyone?


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