Astronomers Detect Four Earth-Sized Planets Orbiting The Nearest Sun-Like Star (ucsc.edu) 102
Tim Stephens reports via The University of California in Santa Cruz: A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water. The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second. The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.
Re:innaccuracy? (Score:1)
Re:30 cm/s (Score:4, Informative)
Fir those who wonder, 30 cm/s is roughly 10km/h, so about the speed of a jogger.
You are off by a factor of 10. It is about 1 km/h, so about the speed of a fast tortoise.
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Is speed of the wobble what was meant? I thought it must be 30cm/second of rotational arc, which translates to a 200km peak variation as the planet orbits from one side 180 deg around to the other.
Re: 30 cm/s (Score:2, Informative)
It is the radial speed of the star b ing measured via doppler shift. It is the speed that the star is moving toward and away from Earth as a result of the orbiting planets' gravitational tug on the star.
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the speed of a fast tortoise.
Great, now I want to watch Tortoise races... I only watch for the crashes.
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so about the speed of a fast tortoise.
It also depends on the type of dog it is.
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Fir those who wonder, 30 cm/s is roughly 10km/h, so about the speed of a jogger.
Yes, but what's that in football fields per centar?
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...U.S. or Canadian football field?
I don't kno..ARRRRRRGGGGGGHHHHHH!!!!!!
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Or did you mean U.S. or Canadian football field?
Fairly sure FIFA's regulations for the size of a football field is same no matter what country: 100-110m by 64–73 m
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Fir those who wonder, 30 cm/s is roughly 10km/h, so about the speed of a jogger.
Yes, but what's that in football fields per centar?
I'd prefer it be expressed in cubic cantaloupes.
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What's a centar?
https://en.wikipedia.org/wiki/... [wikipedia.org] doesn't seem to make sense in context.
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http://www.kobol.com/archives/... [kobol.com]
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Probes are just too danged limited. I really doubt that a probe would have figured out that there is profit to be made from a lethal plant such as tobacco. Humans spotted the opportunity immediately.
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Thus we can conclude: Anything that (in a certain dose) has a lethal effect on us, might have another, may
TAU CETI!!!!!?????? (Score:2)
KAAAAAAHN!......KAAAAAAHN! [youtube.com]
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It is just about possible that we could send a probe that would take 80 years to get there. And then of course we would have to wait another 11 years for it to send back the photograph. Human AI may get to the stars but we are never going there.
Sun gravitational lens (Score:5, Informative)
Re: Sun gravitational lens (Score:1)
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He's referring to Voyager 1, which is about 139 AU (0.002 ly) from Earth. The gravitational lens probe would have to go to 550 AU, which is nearly four times farther than Voyager 1 has made it in 40 years.
It was clear from the first sentence of Katatsumuri's post that the thread had shifted from sending an interstellar probe to sending a local probe, but "local" is still way farther than we've ever managed to send anything (to some extent, because we haven't tried).
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Wow -- this is an awesome idea (even despite the many practical difficulties)!
Other Near Future means of Imaging worlds (Score:2)
This one for example.
Starshade [wikipedia.org]
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I love the concept, but given the difficulty (beyond current tech by at least 1 order of magnitude), expense, and the fact that it could only practically be pointed at a single target for a very brief period of time, you're going to want to be really, really confident there will be something to see with it.
It seems to be that more mundane imaging systems would have to do all the preparatory surveying. It also seems that as technology improves to approach the point at which the Solar gravitational lens meth
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I'm interested how you are proposing to reach an average travel speed of c/7. Isn't that absurdly high?
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Well, I once read a concept paper about it.
But I din't find it anymore. My google fu is leaving me.
The idea was to have a cone like chunk of hard coal, with the probe in its tip.
You drop that with its backend towards our sun. The coal will evaporate and accelerate the probe to roughly 0.2c.
Not sure about the shape, a kind of disk like shape ist likely more suited, as the sun is pretty big that close and you don't want it shine on the probe.
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I think we're still at the phase of our development where there is no point sending out interstellar probes. By the time they get there, either there is no human race left to monitor the info they send back, or we already sent out faster and better equipped probes that overtook them along the way. There is far more within our solar system that we have to study, perfecting the propulsion techniques with gradually increasing distances first.
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Voyager 1 is no longer a probe in a few more years, though (tens of thousands of years before it gets to another solar system). When power runs out, it's an interstellar brick.
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You'll have to ask Ford; they stopped making them in 1997.
Re: closer look (Score:2)
Replicant Bob is already there with his auto factories looking out for Medeiros and the Others.
Getting close to answering a BIG question! (Score:3)
Wow, it appears like we are really getting close to being able to answer the question: are we alone in the Universe?
I'm amazed that they were able to detect the "wobbles" using (relatively) inexpensive ground-based telescopes. Just a little bit of improvement and they'll be able to detect earth sized planets (although maybe 1.7x mass isn't too bad; I think the surface gravity might be just a little higher depending on the density).
Soon, a space based telescope (the James Web ST?) may, with these super-sensitive instruments, be able to take the next crucial step and determine the composition of their atmospheres. If they detect free oxygen or other products of biological (or even industrial!) by-products, we'll know that there's life elsewhere in the universe! Maybe we'll find out sooner this way than a similar positive result coming from a probe we send to Mars, Europa, Enceladus or Titan.
Of course, although I'm hoping that we'll see a biological signal, I really really doubt we'll see something that is the product of a technological civilization. Unfortunately, we still don't know the answer to Fermi's paradox. (I really wish the Chinese would take their new giant radio telescope and dedicate it to looking for signals). Until we hear from someone; we'll have to assume that maybe (intelligent) life in the Universe is rare.
I hope it's not because intelligent life usually kills itself off (like we seem to be doing: https://www.nytimes.com/2017/0... [nytimes.com]
Full disclosure: in my partially misspent youth I worked on S.E.T.I. :)
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All of this exoplanet detection increases the likely value of certain parameters in the Drake equation [wikipedia.org]. And it lowers the uncertainty of those same parameters. This increases the overall odds and confidence that the number of communicative civilizations out there is >= 1, I wouldn't say that it actually brings us that much closer to knowing for sure. A number of the later parameters in
Re:Getting close to answering a BIG question! (Score:5, Interesting)
>we still don't know the answer to Fermi's paradox.
"Space is big. Really big. You just wonâ(TM)t believe how vastly hugely mindbogglingly big it is. I mean you may think itâ(TM)s a long way down the road to the chemistâ(TM)s, but thatâ(TM)s just peanuts to space." - The Hitchhikerâ(TM)s Guide To The Galaxy
I know some space enthusiasts talk about even a single civilization sending out a Von Neumann probe resulting in the whole galaxy being blanketed in a few hundred million years... but space is big, hostile, slow to traverse, and resources are really tough to get access to.
It's very much possible that there's no single answer to the Fermi Paradox, but it's a little bit of all the factors. The base raw materials for life are likely extremely common (similar clouds of gas collapsing into similar systems), but life may be rare and I would expect complex life building technologically advanced space-faring (or even communicating) civilizations to be a fraction of those.
Combine the likely rarity of intelligent life with the massive distances (involving massive time delays)... and you can get a lot of lonely species all thinking there's nobody else out there simply because they can't communicate with each other in any practical way.
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It gets better when you consider 100 ,1000, 10,000 years ago how much we changed. A cell phone would be magic to those just 100 years ago, and amazing tech to those of 75 years ago. You would be burned alive for having one in the 16 and 1700's
Even sending von nueman probes out in a 500 year search would only get them 50-100 light years away.
Maybe if we can build a space ship capable of self mining resources to send additional probes and even additional ships could we begin to explore the galaxy.
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>It gets better when you consider 100 ,1000, 10,000 years ago how much we changed. A cell phone would be magic to those just 100 years ago, and amazing tech to those of 75 years ago. You would be burned alive for having one in the 16 and 1700's
Technological improvements can't overcome the energy required to move a given mass a given distance within a given time. The scale of space is such that sending anything physical that could be expected to survive the journey might not be practical.
We're a bit bett
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Actually, if you are willing to some mathematical speculation, it gets even more depressing.
If the rarity of intelligent life is rare enough, we might actually be entirely alone. Take the busy beaver function [wikipedia.org] for example... it is known that the busy beaver function rises so much faster than any computable function such that one need go no further than BB(25) to get to a number larger than Grahams Number [wikipedia.org], and given that there could be as many as 26 dimensions, even Grahams number may be vastly smaller
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The fact that life formed so early in Earth's history -- pretty much as soon as it wasn't molten -- is suggestive of it not being that hard to form. And enough different types of species have evolved intelligence on Earth to suggest that intelligence is a common result of evolution of multi-cellular organisms. The tricky party really is getting multi-cellular organisms, since that seems to have taken billions of years.
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No, it only suggests that the conditions were sufficient to have some non-zero probability for life.... it does not imply that it was *EVER* particularly likely, and even that says nothing about the likelihood of complex intelligent life other than as a precondition for the latter.
A person can win a lottery the very first time that they ever play... that does not mean that the odds of him winning were ever very high. Similarly, the fact that we exist does not imply any kind of certainty or likelihood t
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I know some space enthusiasts talk about even a single civilization sending out a Von Neumann probe resulting in the whole galaxy being blanketed in a few hundred million years... but space is big, hostile, slow to traverse, and resources are really tough to get access to.
On the other hand we are really impatient because of our human life span. A hundred thousand years travelling and a million years per planet to build up the resources to shoot off another probe is not a blocker if we can only make self-maintaining/repairing technology to last that long. We have attention span of maybe ~100 years, if your grandkids won't see any benefit it's too far out. Then again, given the technological progress we've made in the last 100 years it's probably for the best that we don't foc
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We have a pretty good idea how life forms.
You need an energy gradient, a solvent, and the right mix of chemicals. Life is the arrangement of chemicals that uses the energy gradient to perform the work necessary for self replication.
This statement would have held water in the year 1910. In the year 2017, no.
Life is a HELL of a lot more than "The arrangement of chemicals" Life involves the reading, processing, and self replication of INFORMATION. A self-replicating software program encoded in DNA in every living cell.
The first replicator forms by chance then makes more of itself. Over time imperfections in the copying process lead to diversity among the replicators and scarcity of resources leads to competition which imposes selective pressure favoring more optimal adaptations to the enviroment and eventualy an ecosystem.
This is an unproven article of faith on your part. There is not even a theoretical model of how you go from simple self-replicating chemical reactions to a self contained cell controlled by DNA programming.
What we haven't managed is artificial abiogenesis (ie, manufacturing life in a lab), but that is likely a matter of scale. No one actually wants to set up a multi cubic kilometer proto-life vat and let it run for a million years to see what happens (let alone several). And we have every reason to believe that it took considerably more time and space than that when it happened on Earth.
The math o
Re:Getting close-- Warning built in assumption (Score:2)
We are only getting close if we aren't alone in the universe AND if life isn't rare.
It is pretty hard to prove we 'are alone', so believing we are not is more an act of faith then anything else, until there is evidence. Of which we only have suggestive not positive evidence.
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We're far more likely to be able to detect signs of biological/technological processes in another planet's atmosphere long before we actually hear any radio signals from them. To detect a radio signal things need to happen in just the right way for us to hear it. For atmospheric detection all we need is a spectral analysis. You find CFCs in their atmosphere and it's pretty certain that something a little more advanced than bacteria are on that planet.
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When the term Earth-like is used, it usually means 'rocky planet of approximately the same mass'.
Whether it's the right temperature, has an atmosphere, is in a 'safe' orbit with theoretically tolerable levels of radiation and reasonable temperature variation, tidally locked, etc... all more or less up for grabs depending on who offered the quote and who is reporting it.
I expect the term will end up being more specific as we learn of more exoplanets and improve our ability to determine their characteristics.
Nice (Score:2)
"probably reduces their habitability due to intensive bombardment by asteroids and comets. "
So lots of more water and minerals raining down from the sky.
Good business in the future.
This means we can keep on polluting unabated! (Score:1)
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>If Earth humans had the kind've technologies required to travel to another star system, I would hope that we would,ve also started to use those technologies to clean up and repair damage done to our existing planet.
If humans had the kind of technologies required to travel to another star system, we'd never need to set foot on another planet ever again.
We'd have the ability to build habitable ships that last centuries without resupply or refits. When you can do that... you might want to 'raid' an Oort c
Or. . . . we dis-assemble the Solar System. . . (Score:2)
. . . and re-use the mass to create something akin to an Dyson Sphere [wikipedia.org]. I'd suggest a Ringworld [wikipedia.org], but the mechanical properties [cosmoquest.org] of Niven's "scrith [everything2.com]" simply aren't possible, at least with any level of material science we currently have or are likely to have. . .
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It's Aliens! (Score:1)
Just gotta be. Too soon?
Interplanetary Coconuts (Score:1)
I would like to see a project to begin firing off "seed bags" to every planet we can point a barrel at. Sure, most won't survive but it very well may be one way we can tell what is out there way down the road.
Suppose we found say, these 4 rocky planets, but life hadn't been kickstarted. It seems like it would be our duty to help them thrive. Within 100 years of crash down, we could theoretically see the possible beginning of a planet that could host life like ours.
By searching the cosmos, over the tho