Credit: Illustration by Mark Garlick
But it’s not the only form of rogue world out there.
There’s another type drifting alone amongst the stars, which falls into the category of the ‘brown dwarf’.
Too small to be stars, too bloated for planets, brown dwarves are the duck-billed platypuses of the Universe.
I’m taking the Cruiser Globe to the edge of one of these bizarre, puffed up planetary sub stars: destination ULAS J222711-004547.
Despite a name like three footballers’ Porsche number plates welded together, this brown dwarf promises to be particularly exhilarating.
And since it was discovered by a team from Hertfordshire University led by Federico Marocco, I’m calling it ‘Marocconius’.
With Kraftwerk’s Autobahn on the in-Globe entertainment system, I arrive in no time and hover close, at a distance just half of that between Mercury and the Sun, for a beautifully impressive view of brown dwarf Marocconius.
Strikingly redder than most other brown dwarves, which give off a more violet hue, it shimmers with a deep glow like the side of a red hot oil drum containing the fire on a picket line.
Marocconius’s permanent redness comes from its clouds, which contain a potent brew of water vapour and sizeable particles of the minerals enstatite and corundum;
I never came across those in The Spotter’s Guide to Geology!
I swoop into the cloud deck for a closer examination of these chunky particles, setting the Cruiser Globe’s force field to maximum to withstand travelling directly through this thick blended atmosphere.
The sound is extraordinary, like an almighty hailstorm of Malteser-sized ball bearings – an exhilarating explosion of the harshest white noise imaginable.
Brown dwarf weather is much more glutinous and extreme than that on Earth, as though the weather systems have been thickened up with massive amounts of gravy browning.
The winds here are formidable; thank goodness for the Cruiser Globe’s stability regulators, which minimise the buffeting – and my travel sickness.
I steer an uneasy path flying beneath savage clouds and above the surface of Marocconius.
It looks like Mars in some altered state, all swirling whirls of redness above and a bizarre molten mousse below.
I can’t help feeling like I’m in the film Innerspace, travelling through the human body inside a shrunken submarine.
There’s certainly something unsettling about this brown dwarf.
Could it be modified, I wonder, perhaps by pumping out some of its substance and reducing it to a gas giant double the size of Jupiter?
The excess matter could be used to install some handsome Saturn-style rings, I think to myself as I rise out of Marocconius’s fascinating and ferocious atmosphere.
As I look back at the failed star, I have the urge to put on some suitable music.
Where did I put that experimental duet for steel drum and tuba?
Jon Culshaw is a comedian, impressionist and guest on The Sky at Night
This column appeared in the May 2014 issue of BBC Sky at Night Magazine