Credit: Wikimedia Commons/Public DomainWithin a week of the chimes that welcomed in 2015, two announcements from NASA made it a good new year for exoplanets. News of the Kepler Space Telescope mission finding eight new planets beyond our Sun soon followed confirmation of another six planets discovered by the process of radial velocity (detecting if a star ‘wobbles’ due to the gravitational pull of a nearby planet). We now know of over eighteen hundred exoplanets in our corner of the galaxy, with more certain to follow. Time then we started planning our first vacations to our new-found neighbors, but with so many to choose from, where do we start? To help out, I’ve put together this brief guide to the more exciting exoplanets of the Milky Way to take a break. A very long, and most likely fatal, break.
Let’s say you prefer your home comforts and don’t fancy travelling too far. The nearest likely planet outside our solar system is Alpha Centauri Bb, a measly 4.3 light years away (to clarify, if you travel at the speed of light, roughly 186,000 miles per second, it would take only 4.3 years to travel to Alpha Centauri Bb, so make it at least a long weekend). However, you’ll soon wish you hadn’t bothered, on arriving to find the temperature a toasty 2190F, hot enough to melt rock, tin, aluminium, and your luggage, on a planet so close to its star it exists in a continual state of molten lava.
You’ll find a less warmer welcome on Tau Ceti e, where temperatures hover around the 160F mark, pleasant enough if you’ve the ability to paddle in the geothermal springs of Yellowstone Park without scalding to death. The nearest of the exoplanets that come close to resembling Earth, Tau Ceti e is twelve light years away, but if you’re looking to make new friends, prepare for disappointment. The Tau Ceti system isn’t used to tourists and needs a good spring clean to make itself hospitable to life; the magnitude of Tau Ceti’s debris disc means extinction event-level meteorites impact the Tau Ceti planets far more than Earth. Another down side to vacationing on Tau Ceti e is astronomers aren’t 100% sure it actually exists, such are the vagaries of planet detection, so you’re taking a long shot on this one. On the bright side, if Tau Ceti e does exist, gravity is 1.7 times greater than on Earth, so you can lose weight a lot faster just by walking around.
One of the planets announced by NASA in January, Kepler 438b, is the most Earth-like planet of the known exoplanets, rating 0.88 on the Earth Similarity Index (where 1.00 is a perfect match; by way of comparison, Mars rates 0.64). Temperatures are still a touch uncomfortable at 140F, so grab a spot by the water Kepler 438b may or may not have, and hope the planet has a moon or two to keep the climate on an even keel. You’ll have plenty of space to spread out, as Kepler 438b is over a tenth as large again as the Earth, although you’ll find this a holiday that ages you; as with many exoplanets, Kepler 438b’s orbit is much closer to its parent star than the Earth is to its Sun, with a year taking just 35 days. Still, as it takes 473 years travelling at the speed of light to reach Kepler 438b, I’m guessing age is the least of your Credit: Wikimedia Commons/NASA Ames/W Stenzelconcerns.
For convenience and climate, I’d recommend a trip to Gliese 667Cc. According to statistics provided by the Planetary Habitability Laboratory of the University of Puerto Rico, Gliese 667Cc, at 24 light years distant, ranks fifth as the closest Earth-like world from our own, and has the third highest Earth Similarity Index, of 0.84. This planet is within what scientists call the ‘Goldilocks Zone’, meaning Gliese 667Cc is populated by talking bears which enjoy a bowl of oatmeal. The parent star, Gliese 667C, is part of a three star system, which doesn’t mean it has a three out of five rating on TripAdvisor, rather it is a distant neighbor to the binary star system Gliese 667A and B. Not only would you see the planet’s parent star during the day, over twice as large as the Sun appears on Earth, but the two binary stars would be visible also, and if you feel homesick, our own Sun is just visible at night, so don’t forget to wave. Oh, and cross your fingers as well; solar flares are more common from Gliese 667C’s star type (a red dwarf) and are a thousand times stronger, so let’s hope your timing isn’t off.
Perhaps you’re more interested in an active holiday, taking in some sport or adventure. Well, there are planets out there for you, including the thrill of a lifetime, several lifetimes in fact, at WASP-18b, the doomed planet. Larger than Jupiter, though more massive, WASP-18b takes less than 24 hours to orbit the star to which it will spiral to its demise within the next one million years or so. That may sound a long time away, but so does Christmas, and you know how that can suddenly spring up on you, so book now to avoid disappointment.
For more immediate thrills, ride the rollercoaster of HD80606b, orbiting the star Struve 1341B in the constellation of Ursa Major. This planet is off its rocker, orbiting at an eccentric angle taking it from nine-tenths the Earth - Sun distance from to just 3% of the gap between the Sun and Mercury at closest approach. During the six hours of a month-long orbit when the planet slingshots around Struve 1341B, temperatures double to 2200F and wind speeds approach 10,000 miles per hour, so take a parasol with you, or consider taking up extreme paragliding, or just combine the two.
If it’s water sports you’re after, head for Gliese 1214b, the water world. Too hot for life, with no need to worry about sharks, or octopuses, or sharktopuses, Gliese 1214b sounds like a hot-tub world to me, although some spoil sport scientific ‘experts’ believe the planet is so hot, the world may exist only as a giant ball of steam. If not, it’s water all the way down to an icy core, on a planet twice as big as Earth with enough space for every oil baron oligarch’s yacht collection.
For winter sports, give Gliese 317c a try; scientists are unsure of the exact surface conditions, but estimate temperatures of around -370F, so there’s probably some ice or snow around for you to practice your slalom skills. But what if you enjoy swimming and skiing? Combine the two on Gliese 436b, or the ‘planet of burning ice’ as we hope it gets renamed soon. A planet the size of Neptune, orbiting a star in Leo, Gliese 436b possesses a layer of super-heated water crushed by the planet’s own tremendous gravity to form a substance as hard as ice, yet at over four times over the boiling point of water! Where this leaves your holiday plans I’m not sure, but you’ve got 33 years at light-speed to figure it out. Remember to take a few pictures so scientists can work out what happened to your body when you tried to sample the skiing/swimming scene on Gliese 436b.
After all that excitement, it’s time to ease back and enjoy the scenery. Over at HD 209458b, you’ll find a planet orbiting so close to its parent star its atmosphere is stripping away at an alarming rate, leaving behind a 124,000 mile vapor trail. Pick a nearby vantage point, if there is one, and enjoy the sight, safe in the knowledge that HD 209458b is a broiling, toxic, unpleasant world no-one is going to miss anyway. Catch a cup of water from its vapour trail and toast its own toasting!
The Kepler 11 system has six planets, five of which would fit within the orbit of Mercury, so Credit: Wikimedia Commons/R Hurt (SSC) Credit: NASA/JPL-Caltech/SST.from a distance would look like cars caught forever in a high-speed Wacky Races, if you squinted and used your imagination, while for the younger crowd, there’s CJ504b in the constellation of Virgo, part of system barely into its galactic adolescence at around 150 million years old. Going through an ‘awkward phase,’ CJ504b has colored itself a fetching magenta while maintaining a snooty 43.5 astronomical units from its so embarrassing parent star (1 Astronomical Unit equals the distance between the Sun and the Earth, around 93 million miles).
If you manage to remember its name, then ISWASP J140747-93-394542-6 (the names of celestial bodies are often a mix of galactic co-ordinates and who, or what, discovered them) promises a sight to put Saturn in the shade, a planet with a ring system extending 3.7 million miles outwards, compared to Saturn’s puny 79,000 miles of rubble. Here at ISWASP J140747-93-394542-6 (thank heavens for cut-and-paste) moons the size of Earth clear a path for you to drive around to get the best view. Ample parking, if you can avoid the debris destroying your vehicle.
For the romantics out there, planet HD69830c gives you the sight of an asteroid belt twenty times more massive than that of the solar system’s and a thousand times brighter than Earth’s view of the Milky Way. Yes, HD69830c is the stage for the galaxy’s brightest spotlight, a continual beam reflecting on the (probable) surface water as it ripples with the inevitable constant meteor showers from all those magical rocks up in the sky. Why not carve you and your partners’ initials on one, defying, through the fleeting beauty of love, a universe which wants you dead, and fast? Talking of death, the more gothic will find PSR B1257+12’s system of planets have a charm all their own. The three worlds orbit a pulsar, a normal star which blew up one day and collapsed back on itself to form a super-dense ten-mile wide ball of stuff so radioactive it is detectable from Earth, a thousand light years away. The system is bathed continuously in deadly radiation, but feel free to poke around for what remains of any past civilization before you too, like HD69830c, begin glowing blue and turn lifeless.
Credit: Wikimedia Commons/Blue stragglerIf you really want to get away from it all, I suggest a trip to SWEEPS-11, in close orbit to the snappily named star J175902.67-291153.5. A gas giant slightly larger than Jupiter, SWEEPS-11 is good hike away at 22,000 light years, so don’t forget to take a packed lunch.
Those are just a few of the saner places you can visit in our galactic neighborhood. For some real thrills to tell the folks back home, or at least their descendants, or whatever life-forms are prevailing on Earth once you return (I for one welcome our new insect overlords), COROT-7b for instance offers you the opportunity to experience rain made of rocks. Material evaporating from the daylight side of the planet, where temperatures reach a snug 4000F, condense over the cooler side of COROT-7b, forever shrouded in night, leaving the hardy holidaymaker exposed to showers of iron oxide, silica, spinel and other craft fair favorites. Or how about sideways showers of molten glass? HD 189733b, with its 4350 miles per hour winds, ensures you’ll take part of your holiday home with you, thanks to the magnesium silicate embedded into your body, with the showers slicing across the atmosphere with storms so powerful the ‘rain’ goes right through you – literally! This is a holiday for anyone who has braved a shower strolling along the coastal regions of Scotland.Credit: Wikimedia Commons/ESA - C.Carreau
Of course, these holidays are expensive, but money’s no object if you can reach PSR J1719-1438b, a formerly boring binary star system gentrified when one of the two stars turned supernova, eventually becoming a pulsar. The remaining star, crushed by the pressure generated by the super-dense pulsar, compressed until it turned into a gigantic diamond (imagine how Superman can make a diamond by squashing a lump of coal in his fist, it’s pretty much the same process), orbiting its new pulsar pal at a cozy 0.004 Astronomical Units. Survive the radiation, and you can chip off a few diamonds of your own to finance the trip and any others you care to make.
So there you have it, some of the Milky Way’s prime holiday destinations. Perhaps not for you, but maybe for future generations of humankind, for if there is one reason for us to peer into the darkness and find new worlds it is to bring light, and one day life, where none had existed. If only for that reason we should feel hope when we look up at the sky, and trust in our ability to work together for the greater good, for our future is waiting above us in space, the greatest and most boundless challenge for humanity. For as Ray Bradbury once said, on asked if Martians exist: “One day, we will be the Martians.”