Sun-like star HD10180 thought to have Earth-sized world
Seven-planet system orbits spaced much like ours
Astroboffins probing the skies with a crafty instrument attached to a mighty telescope high in the Andes have found a sun very like our own - which they believe has a planet of similar size to Earth.
“We have found what is most likely the system with the most planets yet discovered,” says top sky-boffin Christophe Lovis. “We are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets."
The planetary system in question is that of the G-type, main sequence star (ie quite like our own Sun) HD10180, lying 127 lightyears away in the obscure southern constellation Hydrus*, between the Magellanic Clouds as seen from Earth.
HD10180 has now been confirmed to have five big, roughly Neptune-sized planets (say 5 to 13 times as massive as Earth) by measurements from the the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph at La Silla in Chile. In addition, Lovis and his colleagues think that there are probably two more - a hefty Saturn-sized job (65 Earth masses) and one which if confirmed would be the smallest known exoplanet at 1.4 Earth masses.
The discovery of a planet not much bigger than Earth orbiting a star very like the Sun might at first seem to be one of trouser-moistening magnitude: but sadly HD10180a is thought to orbit a mere fiftieth of an Astronomical Unit from its star, meaning that it is far too hot to support life along the same lines as Earth. It is so close to HD10180 that its year lasts barely more than a terrestrial day.
Even so, the discovery of HD10180's planetary system does hold great news for alien-fanciers. The distribution of the system's seven possible planets - only one less than ours, as Pluto was never a proper planet in this sense - seems to follow a principle known as Bode's Law (or the Titius-Bode law), a rough rule predicting the spacing of planets from the Sun.
“This could be a signature of the formation process of these planetary systems,” says Lovis' fellow boffin Michel Mayor.
Though the HD10180 system doesn't appear to offer any homes for life, if Bode's Law applies across the galaxy it ought to mean more Earth-like, water bearing planets and so more aliens to meet/get invaded by and/or new worlds to colonise/invade once that pesky hyperdrive has been mastered.
Lovis and his colleagues' paper can be read by those advanced enough in boffinry to follow it here, free in pdf courtesy of the European Southern Observatory - operator of the HARPS. ®
*The male, or lesser, water snake. Not to be confused with the more famous and much bigger constellation Hydra.
Here's how it plays out
* start discovering other planets - keep things low key. only discover gas giants unable to support life.
* discover more and more of these and keep the stories in the media. get everyone used to the idea of other planets.
* start discovering more rocky, earth-like planets - although still of course unable to support life due to position in the star system/composition of the atmosphere. have lots of stories in the media about them.
* finally find an rocky, earth-like planet with all the requirements for life, but none of the signs. start media speculation about what kind of life could be hiding there that we can't see due to technology limitations.
* start finding more and more earth-like planets capable of supporting life, all still with no signs of life however. have lots of media stories about them and statements from scientists claiming that it is now only a matter of time before we discover some sort of life on another planet. get everyone used to the idea.
* find some potential signs of life on one of the numerous earth-like planets, but nothing concrete. Have lots of media stories about the kind of life it might be, but always stressing that it is not INTELLIGENT life, rather that someone has discovered an anomaly in the CO2 levels of the planet in question (or something like that), which could indicate some kind of large algae population or something.
* confirm the above. let the media go bananas about finally discovering life on another planet, always stressing that it is simple life and not in any way sentient or DANGEROUS.
* repeat the discovery of simple life on some other planets, and keep finding evidence to support more complex life forms, starting with perhaps some kind of small worm, eventually leading up to finding evidence for some sort of large herbivore creature.
* keep stories in the media about life on other planets, it's type and origin. again, get everyone well used to the idea, whilst always reassuring everyone there is still no evidence for sentient life anywhere.
* launch some sort of probe to a planet which will take at least 50 years to get anywhere and start returning any data.
* meanwhile, discover a SIGNAL. a very simple one. speculation in the media as to the origin and potential threat.
* discover signal is a beacon, leading to further signal discoveries. scientists begin to try and decipher the new, more complex signals. this takes years and years with no results until...
* eventually the probe lauched years earlier starts returning data which turns out to be vital to deciphering the signal. signal turns out to be a "hello" type affair (not the magazine) and confirms there is other intelligent life in the universe.
* it's official. there's other sentient life out there. everyone is stunned. let everyone calm down a bit and keep stories in the media to get people used to the idea we are not alone.
* eventually, after years of speculation as to the type and intentions of any new sentient life, attempts to send return signals and new probes sent out to other planets, the aliens finally land somewhere very public and say hi. No one is that surprised.
* a new era is born.
is that a ray gun in your pocket....?
Finally, a post with some sense.
Think this through. Aliens won't invade earth for resources. All their mineral and water needs can be plucked out of space, if they can build an intergalactic spaceship they can easily go and mine a comet for water, or thaw out an ice moon, or bring home a 15 mile long uridium asteroid. Why would they invade for conquest? We'd just fight back and frankly it'd be a choice of complete anihilation or they bugger off home when Arnie spanks one in a jungle, and apart from the Polish builders amongst us we're not exactly big on continual manual labour and therefore piss poor slaves. They also wouldn't invade for our technology , they've got a fuckin spaceship.....WTF do they need a Wii for?
On the other hand, the most likely reason for invading would be like a smokers trip to Amsterdam. Face it, they're just like sailors but in space, so when they find an inhabited planet the first point of call is get wasted and laid.
I call this the universal law of poontang aquisition. Eventually, when technology exceeds the limitations of watching pron, society builds space ships and heads off to another planet where the women/men** may be impressed by intergalactic travel and put out big time.
**delete preference as necessary.
True - but...
I agree with your comment about Avatar (although I have read that James Cameron was quite careful with his space science), but consider the case of Saturn and Titan. Place Saturn in the "Goldilocks" zone and Titan could become quite a nice place to be for life. The same could also be said for Jupiter and Europa although there could be major issues regarding Jupiter's radiation belts (this might drive evolution faster through mutations though).
Regarding the day/night cycle, I not sure if this is a difficulty. We have a similar problem on Earth inside the artic and antartic circles and life does work in these zones, granted it's hard. A moon of a gas giant will have periods of eclipse but these periods will be short.
What could be more difficult are the orbital dynamics. Going back to Titan again, Titan has an orbital period around Saturn of about 16 days. It is also tidally locked to Saturn, that is it's rotational period matches it's orbital period, so it has a "day" of 16 dfays too. That means that Titan will have 8 (Earth) days of Sunshine and 8 days worth of darkness. This is actually quite less extreme than the situation in our polar circle regions so I feel that this could be quite managable for terresial type life. Eclipses could complicate things as these would last a few days during the daylight cycle but I don't know enough about Titan's orbit at the moment to comment on the frequency of such eclipses, I suspect that Titan's obital inclination takes it out of Saturn's shadow cone quite a lot.
The situation for Europa becomes much more easy as Europa has an orbital period of 3.5 days around Jupiter giving a 1.25 daylight/night cycle(it is tidally locked to Jupiter), much closer to our own. In the cases of eclipses for Europa these will happen every daylight period as Europa is too close to Jupiter to avoid Jupiter's shadow cone, but they should only last a few hours.
In all then, different, perhaps difficult, but not impossible for life to get going and to become complex on such a moon. I think these are very exciting possibilities and given the current state of exoplanet hunting I think these possibilites are more likely than not.
These are exciting times!