Exoplanet Excursions: October 2014

Jon heads into the Milky Way’s bulge, to a region where the stars are legion.

One of my greatest astronomical fascinations is imagining the kind of night sky visible from the centre of our Galaxy, that massive sphere of densely packed stars called the ‘galactic bulge’.

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Credit: Illustration by Mark Garlick

How would such an unfathomable plethora of stars appear to our eyes?

A good exoplanet to provide this kind of saturated starlit view has the catchy name of MOA 2011 BLG 293 Lb. I’ll call this planet ‘Meridanis’, if I may, to reflect its central position in the Milky Way. This was the first planet to be discovered in the habitable zone of a star in this most crowded part of the Galaxy. This particular star is G Class and reassuringly similar to our Sun, though a modicum smaller.

Upon reaching Meridanis, there’s a Mars-sized exomoon in orbit, which will be the perfect place to settle and make our observations. At the time of landing, there’s an hour until the parent star sets.

A sunset in the galactic bulge promises to be quite unlike any view yet witnessed on our excursions. The sky here has a purple hue and such is the staggering number of stars present they appear with a blurry iridescence even when the daylight of the parent star dominates. It’s a beautiful marbled effect similar to an opalescent paint finish on a hairdresser’s car.

As the star continues setting there isn’t a gently deepening dusk. In Earth skies, planets and stars appear individually and gradually: Venus, Jupiter, Arcturus and so on. The stars appear in a dramatically different way here. Over Meridanis, a huge swathe of stars appear with a rapid, mesmeric glow, which reminds me of  the Sun’s corona searing into view during the totality of a solar eclipse.

Every square inch of sky is compacted with pin points of stelliferous light; stars so close together they’re affected by one another’s gravity. As well as stars, garlands of nebulosity glow in deep orange, blue and indigo.

Here, there isn’t a night-time light we’d be familiar with. Such a colossal number of stars generate a glow evocative of an artificial electric light on the grandest scale; a silvery monochrome illumination casting shadows in innumerable directions. By starlight alone, I can read my Observer’s Book of Astronomy really quite easily.

The gas giant Meridanis is itself an incredible, ominous sight, visible from my position in its ‘new’ phase. It occupies about a quarter of the sky, a solid, lightless black hole amid the infinite density of stars. Only its thin ring system shimmers, like the famous image of the backlit Saturn.

One drawback here is how tricky it is to conduct any kind of astronomy. A sky so awash with light makes it extremely challenging to study objects in much detail. We can consider ourselves very lucky that our Solar System is akin to Kielder or Sark – a precious dark-sky site tucked away in a backwater of a spiral arm of the Milky Way. The opposite extreme, our journey to the centre of the galaxy to witness the overpowering splendour of the Meridanis sky, has been spectacular indeed.


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

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

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