Diamonds in the sky: Seven fantastic planets
For most of human history, the solar system was enough of a treasure trove of cosmic wonder to hold stargazers' attention.
But as for what might lie beyond, that was the realm of imagination -- Until scientists pointed more and more powerful telescopes at a handful of stars and started spotting whole other planets.
We’ve spied almost a thousand of these "exoplanets" so far, with more being revealed all the time. And we’ve discovered that some of them are even more outlandish than anything Star Trek has ever managed to come up with.
Here are seven of the most fantastic worlds scientists have discovered (so far).
COROT-7b: Cloudy, with a chance of molten rock rain
Here's a nice, unassuming world a little under twice the diameter of Earth, with a year that lasts around 20 hours.
Also: Molten rock rains from the skies.
Like Mercury, COROT-7b is tidally locked, so one side is always facing its parent star, while the other is always in darkness.
But it’s 23 times closer to its star than Mercury is to our sun, so we’re talking day-side temperatures of around 2,300 degrees Celcius… hot enough not just to melt rock, but also to vaporize it.
So it DOES have an atmosphere, but it’s thin, blazing and made up of evaporated silicates, possibly arising from molten lakes or oceans.
And when a front moves in, some of that horrible atmospheric stew condenses into pebbles, which rain back down onto the stygian lava pools that spawned them.
Later research found the atmosphere is probably too thin to form clouds of any kind, and that nightmarish worlds like this may be common enough to be their own separate class of “lava-ocean planets.”
Which is an important discovery, but we prefer the other kind of ocean planet – of which there are plenty.
GJ 1214b is a hot and steamy ocean
And here comes GJ 1214b, obliging us by being covered in a ocean of water, rather than a hellish mix of molten rock.
New scans of this planet last year suggested that not only does the planet have an atmosphere of water vapour, it boasts much higher ratio of water than our homeworld, and comparatively less rock (it’s about seven times Earth’s mass).
But if you’re picturing a world of pristine and peaceful waves, or even planet-wide hurricanes, the planet’s discoverers are quick to crush those hopes.
The planet is really hot, around 230 degrees Celcius. Those temperatures, combined with high pressures, do weird things to all that liquid. Researchers throw around terms like “hot ice” and “superfluid water” to describe liquid or semi-liquid states that just don’t exist on Earth outside of a lab, but could be abundant on GJ 1214b.
But it may have once been a more welcoming water world. The theory is, GJ 1214b formed further out from its parent, and was slowly pulled closer during the solar system’s early history, possibly spending a few eons in the habitable zone with Earth-like temperatures.
NASA and the European Space Agency are keeping an eye on this one.
Kappa Andromedae b is 13 times more massive than Jupiter
Here’s Kappa Andromedae b, glowing bright red in this artist’s rendering from NASA. And it’s enormous.
At 13 times Jupiter’s mass, NASA says it’s hovering just at the threshold between a “super Jupiter,” and a brown dwarf, a stellar body which, for whatever reason, didn’t fire up the fusion process to burst into life as a star.
Translation: If this planet were any bigger, it would be a failed sun (Its parent star, Kappa Andromedae, isn’t too shabby either, at 2.5 times the mass of our own sun).
Planets larger than Jupiter are actually not too uncommon. WASP-17b, for example, is around twice the radius of Jupiter (seen beside it for handy comparison below), but only half as massive.
Its density is also so low, it could float in water if you could find a bathtub big enough to hold it.
Aaaaaand at the complete opposite extreme, here’s Kepler-37b:
It’s the smallest known exoplanet (so far)….a little larger than Earth’s moon, which should give you an idea of how precise our planet-detecting techniques are getting.
WASP-12b is being devoured
If you wonder what a planet would look like while it’s halfway down the gullet of a hungry star, look no further than WASP 12b:
And you’d better take a good, long look … NASA reckons the distant gas giant only has another 10 million years left before it’s a memory (sounds like a lot, but it isn’t. Earth, remember, is more than 4.5 BILLION years old).
Naturally, being that close to a star has had a catastrophic effect on the planet.
It takes only a little over a day to zip around its parent, and the enormous tidal forces are what give it that egg-like shape in the artist rendering above.
It’s also sweltering, at around 1,500 degrees Celcius (It was the hottest-known extrasolar planet at the time of its discovery in 2010), and its atmosphere is bloated to around three times the radius of Jupiter, despite being only 1.4 times as massive as our solar system’s resident giant.
Shame it’ll be gone so soon … research suggests the doomed planet has a very high carbon ratio in its atmosphere. Carbon is found in most forms of life on Earth (though don’t hold your breath about life on WASP-12b), and carbon-rich minerals include graphite – and diamond.
What, a diamond world seems a little too far fetched? Well…
55 Cancri e might be made of diamond
Yep, diamond. About a third of 55 Cancri e could be made of the precious rock. Seeing as how the planet’s about eight times as massive as Earth, if you were to mine all that diamond out in one piece, the shiny result would be almost three-times bigger than our entire home planet.
It’s about 25 times closer to its parent star than Mercury is, orbits so fast its “year” only lasts about 18 Earth-hours, and its surface is super-heated to around 1,700 degrees Celcius.
To give you an idea on how fast the science of exoplanets is changing, when 55 Cancri e was first discovered in 2004, researchers thought it was a dense planet of solid rock.
Then, as recently as 2011, another theory held that up to a fifth of the planet’s mass was actually light elements and even water – heated into a “super-critical” state (basically super-hot and dense steam):
Don’t worry about it causing a price-crash, though. Although the Cancri 55 system is only 40 light years from earth (close enough for the star to be seen with the naked eye), that’s still almost 400 trillion kilometres away.
The triple sunsets of Gliese 667 Cc are awesome
This shot of dusky peace could just as well have been taken in the waning afternoon hours above the Grand Canyon, were it not for minor detail of the three suns in the sky:
That is Gliese 667 Cc, one of six, possibly seven, planets warmed by the red dwarf Gliese 667C and its two sister stars, around 22 light years away. And aside from hosting a fine show every evening, the weather may be decent too.
Three of the system’s planets, including the pretty one up there, are “terrestrial worlds” in the star’s habitable zone, meaning they’re almost certainly capable of sustaining some form of life.
There are a few differences between Gliese 667 Cc and Earth. It receives only around 90 per cent of the solar radiation we get, but the authors of this paper say it’s likely a little warmer than our planet.
As for the climate, that depends on how dense the atmosphere is, and also where the land masses are (or even if there are any oceans), although researchers say the planet’s 28-day year may mean it has no jet stream and no deserts.
So it’s not quite Luke Skywalker’s home planet, but with (likely) no deserts and three suns rather than Tatooine’s meagre two, we’re prepared to call it an upgrade.
There are orphan planets wandering between the stars
If the plethora of new worlds being spotted around distant stars isn’t enough, it turns out some planets don’t even NEED stars.
Check out this world, CFBDSIR 2149-0403:
It’s just kind of meandering through the dark space between the stars. It seems to shine blue-ish at around the 0:20 mark, since in visible light, it would be too dark to see without a star to illuminate it.
Its discoverers say it likely weighs up to seven times as much as the planet Jupiter, and its atmosphere may contain methane and water vapour.
Incredibly, it even has its own parody Twitter account:
I'll just show up in your Solar System...Unannounced. #LetsMakeItAwkward— CFBDSIR 2149 (@CFBDSIR_2149) December 10, 2012
As with many of its fellow interstellar orphans, astronomers haven’t been able to determine whether it formed out there in the space between the stars, or if it was somehow ejected from its home system.
There isn’t even consensus on whether these are proper planets at all. Many scientists prefer to classify them as brown dwarves, which are basically pre-stars that failed to actually burst into life.
A planet without a home seems far fetched, at least until the first one was discovered a few years ago, but new research says these nomads might drastically outnumber system-planets, or even stars.
Another rogue planet, Cha 110913-773444 even seems to have its own planets, although opinion is split on whether it’s a rogue planet with moons or a brown dwarf with planets.
And, incredibly, some researchers say a rogue planet’s gaseous atmosphere may even have retained enough heat to support crude microbial life.
Sooner or later, someone is bound to find iron-clad evidence that one of the hundreds of exoplanets discovered is absolutely guaranteed to support life. Until then, though, the ones we've found are incredible enough.