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Nearby Star May Have More Planets Than Our Solar System

Unknown Lamer posted about 2 years ago | from the told-you-space-lizards-were-real dept.

Space 102

The Bad Astronomer writes "HD 10180 is a near-twin of the Sun about 130 light years away. It's known to have at least six planets orbiting it, but a new analysis of the data shows clear indications of three more, for a total of nine! This means HD 10180 has more planets than our solar system. And whether you think Pluto is a planet or not, all nine of these aliens worlds have masses larger than Earth's, putting them firmly in the 'planet' category."

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102 comments

Manic Hispanic (-1)

Anonymous Coward | about 2 years ago | (#39602511)

From the Planet PUTO.

Yes, but... (3, Informative)

mmullings (1142559) | about 2 years ago | (#39602547)

So, how many of you saw HD 1080i

Re:Yes, but... (3, Funny)

pushing-robot (1037830) | about 2 years ago | (#39602627)

Researchers claim that the increased number of planets makes this star far more interesting than its companion, HD 7120.

However, it takes sophisticated equipment to detect the additional planets; most amateur astronomers can't see the difference with their smaller telescopes.

Re:Yes, but... (4, Funny)

mwvdlee (775178) | about 2 years ago | (#39602667)

HD 1080i has only half the planets of HD 10180, it just looks the same as it's an interlacing solar system.

Re:Yes, but... (4, Funny)

Penguinisto (415985) | about 2 years ago | (#39602727)

So, how many of you saw HD 1080i

Sorry, my telescope only does 720p.

I'll have enough saved to upgrade in a month or two, though.

Re:Yes, but... (0)

Anonymous Coward | about 2 years ago | (#39607761)

COME ON ALREADY, GIVE ME MY HD 4K, WITH MORE PLANETS THAN YOUR MOM HAS BOYFRIENDS.

<Insert anecdote about my IBM T221, which is 10 years old and blows away every other monitor ever, and conspiracy theory about how the TV industry is deliberately running a slow upgrade treadmill to make everyone buy one at every step...>

Then we must attack! (2)

stevegee58 (1179505) | about 2 years ago | (#39602587)

We cannot stand by and allow this "planet gap" to continue! Earthlings unite!

mass? (2)

Pieroxy (222434) | about 2 years ago | (#39602649)

I thought Pluto was 'degraded' of its planet status because it wasn't orbiting the sun in the same plane as the other planets, not because of its mass...

Re:mass? (4, Informative)

meglon (1001833) | about 2 years ago | (#39602721)

It's because it hasn't cleared it's neighborhood of other objects (not including it's moons). Pluto is basically one of the largest objects in a debris disk. Had it accreted that disk, we'd still call it to planet.

Re:mass? (1)

Anonymous Coward | about 2 years ago | (#39604181)

Note that Pluto's debris disk, the Kuiper belt, overlaps the orbit of Neptune, which is about 10000 times as big as Pluto. We'd say that Neptune accreted Pluto, not the other way around.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39602737)

Not exactly, but yeah, mass is not the determining factor to whether a stellar body is a planet or not. It is more about the orbit.

Re:mass? (5, Informative)

Anonymous Coward | about 2 years ago | (#39602783)

The current IAU definition is (c/o Wikipedia)

The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet"[1] is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape[2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects[3], except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".
Footnotes:
1 The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2 An IAU process will be established to assign borderline objects into either "dwarf planet" and other categories.
3 These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
The IAU further resolves:
Pluto is a "dwarf planet" by the above definition and is recognised as the prototype of a new category of trans-Neptunian objects.

Pluto fails because it hasn't cleared its orbit.

Many people don't like the definition for many reasons. Among them, that what constitutes a "clear" orbit is not specified and is arbitrary (no planet has an orbit 100% free of other objects), that the point of 'hydrostatic equilibrium' is also unspecified and arbitrary, and that it only applies to the Solar System ("The Sun" is in there).

Re:mass? (1)

avonhungen (108123) | about 2 years ago | (#39602821)

I think most folks would agree it fails 1b as well

Re:mass? (2)

Chris Burke (6130) | about 2 years ago | (#39602907)

Not really; as far as we can tell Pluto is roughly spherical, and has sufficient mass to reach hydrostatic equilibrium.

Re:mass? (4, Funny)

ColdWetDog (752185) | about 2 years ago | (#39603119)

Not really; as far as we can tell Pluto is roughly spherical, and has sufficient mass to reach hydrostatic equilibrium.

So are my neighbors. In addition they've cleared a debris field that encompasses 'the neighborhood' (McDonald's, KFC, Wendy's and both grocery stores).

Should i report them to the IAU?

Re:mass? (1)

Chris Burke (6130) | about 2 years ago | (#39603179)

Well in contrast to bodies in space, their inability to clear their debris field is most likely a direct consequence of their great mass. So calling them "dwarf humans" would be highly inaccurate.

Re:mass? (1)

Kjella (173770) | about 2 years ago | (#39605893)

Well they also need to have celestial bodies, each to his own but I wouldn't describe those as heavenly...

Re:mass? (1)

mister_playboy (1474163) | about 2 years ago | (#39604265)

The amount of mass needed to self-round is far below the amount possessed by Pluto.

Saturn's moon Mimas [wikipedia.org] would be our best cutoff example found.

Re:mass? (1)

Chris Burke (6130) | about 2 years ago | (#39602883)

Many people don't like the definition for many reasons. Among them, that what constitutes a "clear" orbit is not specified and is arbitrary (no planet has an orbit 100% free of other objects), that the point of 'hydrostatic equilibrium' is also unspecified and arbitrary, and that it only applies to the Solar System ("The Sun" is in there).

Those people ignore that there's a five order of magnitude difference [wikipedia.org]

between the least of the planets is, versus the greatest of the dwarf planets.

The line between Europe and Asia is arbitrary. The line between Eurasia and the Americas is absolutely not -- you could draw the line with a brush a thousand miles wide. The situation in our solar system is the latter case.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39602959)

The problem isn't how fine the line is, the problem is that it's entirely arbitrary. People don't like arbitrary definitions in science.

Re:mass? (0)

Chris Burke (6130) | about 2 years ago | (#39603101)

There's nothing arbitrary about a 5-orders-of-magnitude difference in gravitational dominance. It's an obvious difference between objects in our solar system that should be acknowledged. Ignoring it would be stupid.

"People" don't like that Pluto got demoted; their objections to the definition are reverse-engineered from that emotional fact, as evidenced by not even trying to understand the physical reality that informs it.

Well guess what, Pluto fans? You're not much of a Pluto fan if your love is based around it being technically called a planet. The object is still just as awesome as it used to be. The only thing that changed is our understanding of its place in the solar system.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39603249)

Arbitrary means that the line has been drawn at a certain point because... we decided to draw the line at that point. There's no "physical reality" there, it's just a certain terminology that we've decided feels right. That type of definition makes some people uncomfortable. And how do we apply it to other star systems, or star systems in different stages of development?

And I don't think all of the people who have issues with the definition are "pluto fans". That's an unfair characterization. I can understand the complaints, and I certainly don't care about the the little rock any more than any other trans-neptunian object.

Re:mass? (3, Insightful)

Chris Burke (6130) | about 2 years ago | (#39603309)

Arbitrary means that the line has been drawn at a certain point because... we decided to draw the line at that point.

Well they didn't draw the line at a certain point because they didn't have to. The extant gap between bodies' orbit-clearing ability was already there and ridiculously huge. It's no more arbitrary than the distinction between the Americas and Eurasia. You might not be able to exactly where one begins and the other ends, but you don't have to because there's a gigantic gap where neither of them are.

Complaining "Why did you pick exactly that point?" when no point was picked, the 5-order-of-magnitude gap makes such a thing unnecessary, is missing the point.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39603763)

But again, that might not work for extra-solar star systems.

I use the dwarf planet / planet distinction, don't get me wrong. I also like dividing the bodies into 'region'-based categories. Inner planets, inner dwarf planets (asteroid belt planetoids), gas giants, ice dwarfs.

Re:mass? (1)

Chris Burke (6130) | about 2 years ago | (#39612685)

But again, that might not work for extra-solar star systems.

That's why limiting the definition to our solar system is actually a feature. :)

I use the dwarf planet / planet distinction, don't get me wrong. I also like dividing the bodies into 'region'-based categories. Inner planets, inner dwarf planets (asteroid belt planetoids), gas giants, ice dwarfs.

Which is great. As Neil Tyson said in an interview once, to him the important thing wasn't whether you called something a planet, it was what the properties of the object were. You have a big table of the objects and their properties, and if what you're interested in is icy bodies that have achieved hydrostatic equilibrium but not cleared their orbits, then you get a set of bodies that match that. And so on.

To me personally, I don't care about the word "planet" or "dwarf planet". I don't care what you call these things. I just care that we acknowledge extant differences between them -- such as that there are 8 objects orbiting the sun that have the ability to clean up their orbits of the vast majority of debris, and the rest which cannot even come close.

Separating Pluto from those 8 bodies isn't arbitrary. Neither is wanting to include it with them. The difference is that the latter is based on history and nostalgia, the former on science.

Re:mass? (1)

king neckbeard (1801738) | about 2 years ago | (#39604391)

Yes, there is a 5-order-of-magnitude gap in our solar system, but there are other systems, and they may have celestial bodies that fall within that gap, so clearer terms might be useful.

Re:mass? (3, Informative)

Mal-2 (675116) | about 2 years ago | (#39604593)

Yes, there is a 5-order-of-magnitude gap in our solar system, but there are other systems, and they may have celestial bodies that fall within that gap, so clearer terms might be useful.

Since we don't yet know the composition of these other systems (though I think most would grant they should exist), shouldn't the defining be similarly deferred? Make the definition as useful as it needs to be now, tighten it up later when it's clearly inadequate. It's an imperfect process, but it worked before and it will work again (Pluto controversy notwithstanding). "Planet" is a name for a class of objects, and perhaps overly broad, but right now it usefully defines what we know. When we know more, we'll muck with the definition to fit.

Re:mass? (1)

dissy (172727) | about 2 years ago | (#39603925)

Yeay, it's car analogy time!

So imagine a new rule is passed for a particular road which that states "Only motorized vehicles of car size or larger are permitted"

While the rule of "motorized" is arbitrarily drawn, arguing pluto is still a planet is akin to arguing that your roller skates should be allowed because they both have wheels and the human body is a motor.

You then follow by presenting evidence your roller skates should be labeled a motor vehicle because they are technically more like a jeep, and the line between a jeep and a car is so small as to not be worth mentioning... All the while not realizing the scale of difference between roller skates, and either a car or a jeep.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39605511)

Ya know, sometimes someone has to draw an arbitrary point to start from...it may get refined in future but humans making arbitrary distinctions in a field as young as planetology is perfectly fine to this scientist...in fact until all the recent IAU kerfuffle, even the definition of a planet was relatively arbitrary...(this is a planet and that isn't) etc

Re:mass? (1)

Randle_Revar (229304) | about 2 years ago | (#39603455)

The anti-Plutites are absurd, even as they deny it is a planet, they simultaneously admit it is, by calling a dwarf planet. A dwarf mammoth is still a mammoth, after all.

Re:mass? (2)

mister_playboy (1474163) | about 2 years ago | (#39604301)

"People" don't like that Pluto got demoted; their objections to the definition are reverse-engineered from that emotional fact, as evidenced by not even trying to understand the physical reality that informs it.

Indeed. Not only is Pluto no longer a plant, it no longer can claim Charon as its moon. Pluto and Charon orbit a common center of mass outside of both bodies, making them a binary planet with a further two (or possibly more) small moons.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39603131)

But in that sense the definition isn't arbitrary: Pluto and Mars are clearly in a different category. Of course you could argue that all names arbitrary and that the current current nomenclature is as arbitrary as calling them xulphydsfs and wchmfups instead of planets and dwarf planets, but that shouldn't stop us because that would preclude all communication and hence science.

Re:mass? (1)

arth1 (260657) | about 2 years ago | (#39604379)

But in that sense the definition isn't arbitrary: Pluto and Mars are clearly in a different category.

Different from the rest of the solar system? Yes. Neither Pluto nor Mars clears its own orbit. Phobos, Deimos, Nix and Hydra are good evidence of that - they're captured debris that wouldn't have been there in the first place if the orbit had been cleaned.

I think a more reasonable definition is what a passing alien would see. In which case the answer would likely be four or six planets. Two gas giants, two ice giants, and perhaps two rocks. The rest is various smaller debris, which includes satellites and smaller objects like Mercury, Ceres, Mars and Pluto.

Re:mass? (1)

Gavagai80 (1275204) | about 2 years ago | (#39603811)

The lines between Asia and Africa or North and South America, would be a better comparison. There was a land connection before the canals, but so much smaller of a land connection than between Europe and Asia that it becomes obvious to draw a distinction.

Re:mass? (1)

Black Parrot (19622) | about 2 years ago | (#39603107)

Pluto fails because it hasn't cleared its orbit.

So get in there and clean your room, or you'll never amount to anything!

Re:mass? (1)

Surt (22457) | about 2 years ago | (#39603501)

I don't like it because the IAU aren't the most qualified scientific organization to construct a definition.

Re:mass? (0)

Anonymous Coward | about 2 years ago | (#39606627)

(a) is in orbit around the Sun - I think this disqualifies the newly found planets from having that title.

But... but.... (1)

halivar (535827) | about 2 years ago | (#39602665)

...but [i]we[/i] have nine planets [i]too[/i]!

Justice for Pluto!

Re:But... but.... (1)

halivar (535827) | about 2 years ago | (#39602687)

Damn those bb forums and their tags, and damn those previews for letting me click through them without retyping the whole message!

Re:But... but.... (1)

Randle_Revar (229304) | about 2 years ago | (#39603487)

We also have Ceres, Eris, Makemake and whatever the other one is called, Haumea or something. And maybe Charon, if you roll that way.

We've Got This (0)

Anonymous Coward | about 2 years ago | (#39602701)

Between Tyche and Planet X, I think we can win!

are they all in the habitable zone? (2)

modmans2ndcoming (929661) | about 2 years ago | (#39602711)

Could this be the place we escape to when the earth is uninhabitable? Will we live in a space western?

Re:are they all in the habitable zone? (0)

Anonymous Coward | about 2 years ago | (#39602767)

No.
If the star is larger than our sun, and they're in an orbit closer than mars to our sun, they likely aren't in a habitable zone at all.
Maybe the furthest out, but the size measurements make it unlikely to support life at that distance.

Re:are they all in the habitable zone? (1)

Anonymous Coward | about 2 years ago | (#39602849)

I think the formula for creating & perpetuating "life" is (in part) a function of star-radiation/planetary-gravity, within a certain range. You can be a little closer and a little smaller, or a lot further & a lot larger, than Earth. We are kinda near the inner limit, with our mass. I mean, it's just a theory...

Re:are they all in the habitable zone? (2)

Black Parrot (19622) | about 2 years ago | (#39603135)

Could this be the place we escape to when the earth is uninhabitable? Will we live in a space western?

No, it's the place prepared for our afterlife.

If you're good, you get to float around the clouds of the gas giants playing a harp. If you're bad, you spend all eternity assembling smartphones on one of the scorching inner planets.

Firefly System? (2)

Jhyrryl (208418) | about 2 years ago | (#39603407)

You're asking if this is the planetary system from Firefly.

Re:Firefly System? (1)

modmans2ndcoming (929661) | about 2 years ago | (#39604171)

ding ding ding ding.....

I know there are fewer planets than in Firefly, but still....It took that long for someone to get it?

Re:Firefly System? (0)

Anonymous Coward | about 2 years ago | (#39608871)

We all got it but most didn't think it worth commenting on

HD 10180 Nearby? (2)

aslvstr (659823) | about 2 years ago | (#39602741)

When did 130 ly become nearby? Did someone invent a FTL drive while I wasn't paying attention?

Re:HD 10180 Nearby? (4, Interesting)

Grayhand (2610049) | about 2 years ago | (#39602857)

When did 130 ly become nearby? Did someone invent a FTL drive while I wasn't paying attention?

Light coming from it is only a 130 years old not millions or billions of years old. I think the general unspoken idea of nearby is that they may still have the same technology if there were intelligent life that they did a 130 years ago so there's the potential for contact if a civilization was detected. There is a likely window of a few hundred years to a few thousand years where contact would be possible. There is no set standard for nearby but I think that would be the closest I could come, any star with the potential for contact. 130 light years is definitely in that range and with multiple large planets it'd be a solid candidate for life.

Re:HD 10180 Nearby? (0)

Anonymous Coward | about 2 years ago | (#39602885)

Around the time that 130 became less than 100 million.

From : http://www.atlasoftheuniverse.com/virgo.html

      Number of stars within 100 million light years = 200 trillion

Re:HD 10180 Nearby? (0)

Anonymous Coward | about 2 years ago | (#39602965)

It's always been nearby. Nearby is a relative term. Whether your scale is the galaxy, the local galactic super cluster, or the entire universe, 130 light years away is practically right on top of us. The top of the redwood tree I am sitting beneath is "nearby" even though I have no way of getting up there.

Re:HD 10180 Nearby? (4, Insightful)

Chris Burke (6130) | about 2 years ago | (#39603475)

When did 130 ly become nearby?

As soon as the context became the stars.

Re:HD 10180 Nearby? (0)

Anonymous Coward | about 2 years ago | (#39604759)

I don't think any object that no human being can visit in their lifetime without defying the laws of physics can be truly said to be "nearby".

Re:HD 10180 Nearby? (4, Informative)

rachit (163465) | about 2 years ago | (#39604793)

I don't think any object that no human being can visit in their lifetime without defying the laws of physics can be truly said to be "nearby".

You *can* visit it in your lifetime without violating the laws of physics, its just that you cannot visit it in the lifetime of the people observing you from Earth.

Huh, I guess I'll be the first (1)

mdenham (747985) | about 2 years ago | (#39602749)

...to bring up Firefly and its "dozens of worlds" in one solar system.

Yes, I know it's horribly inaccurate with respect to pretty much every detail on this solar system. I don't care; it's better than stupid resolution jokes.

Re:Huh, I guess I'll be the first (1)

tragedy (27079) | about 2 years ago | (#39603819)

There are 9 (8) planets in our solar system with an additional 20 large moons and a good 100+ smaller ones. After that, there's a good number of solidly large asteroids. A single (or binary) solar system with dozens of worlds doesn't really seem that far-fetched when you consider how many we have right here. Admittedly a good number of them are so far from the sun that the local temperatures measure in the double digits on the Kelvin scale.

Explanation (0)

Anonymous Coward | about 2 years ago | (#39602755)

We have Jupiter, hence less planets.

Nibiru to the rescue! (3, Funny)

Trails (629752) | about 2 years ago | (#39602765)

Yeah but when nibiru comes back around, we'll be up a planet and then who'll be laughing?

Re:Nibiru to the rescue! (1)

Cazekiel (1417893) | about 2 years ago | (#39603071)

Now is the time to make Ceres a planet. Our fragile, blue-speck egos need it.

Re:Nibiru to the rescue! (0)

Anonymous Coward | about 2 years ago | (#39603181)

Not necessary if you call Pluto a planet, as Eris is more massive than Pluto.

Re:Nibiru to the rescue! (0)

Anonymous Coward | about 2 years ago | (#39603757)

Correct me if I'm wrong, but isn't Niburu supposed to be a brown dwarf? So we will be a binary system. It'll make us look even more pathetic. "Look! They have two stars and all they can manage is a lousy eight planets!"

only Solar System can have planets (1)

khallow (566160) | about 2 years ago | (#39602779)

The definition of planet is such that only the Solar System can have them. And as already noted several times, higher mass isn't enough to be a planet. It also has to have "cleared its neighborhood", whatever that means.

Re:only Solar System can have planets (2)

gstrickler (920733) | about 2 years ago | (#39602873)

You narcissistic xenophobe. Sol is not superior to other suns.

End Solar Supremacy! We demand equal treatment of all planetary systems.

Re:only Solar System can have planets (0)

Anonymous Coward | about 2 years ago | (#39603463)

Sure support just the one's with planets. What is it with some people? Just because a Star doesn't have a body of planets doesn't mean it's somehow inferior. I object to your term planetary and expect a retraction. good day sir!

Re:only Solar System can have planets (0)

Anonymous Coward | about 2 years ago | (#39603233)

"Cleared it's neighborhood' means that if a planet sized object is in an asteroid belt, then it's just a big asteroid. To be a planet it has to have cleared out any such debris near it's orbit.

Re:only Solar System can have planets (1)

khallow (566160) | about 2 years ago | (#39603515)

"Cleared it's neighborhood' means that if a planet sized object is in an asteroid belt, then it's just a big asteroid. To be a planet it has to have cleared out any such debris near it's orbit.

No, that's not what it means. In the paper which coined the term, it was noted that the eight planets dominated the rest of the mass in their "orbital shell", the spherical shell centered on the Sun with inner and outer radii the object's closest and most distant approach to the Sun with several orders of magnitude gap between those planets and "dwarf planets". And it's worth noting that there still isn't an official definition of the term (despite the definition being coined six years ago).

Re:only Solar System can have planets (1)

Surt (22457) | about 2 years ago | (#39603479)

That's a definition, not the definition of a planet. And it's the IAU at that, who are hardly experts in the field.

Not to be pendantic, but... (0)

Anonymous Coward | about 2 years ago | (#39602807)

None of these objects are firmly in the "planet" category according to the technical definition.

First, the definition only includes objects in our own solar system. Exoplanets are not a subset of planets, they are a different class of objects altogether.

Second, even if we were to fudge the definition to include extrasolar planetoids, size doesn't matter. (Cue "that's what she said" jokes) Part of the definition of a planet is that is must have cleared its orbital neighborhood of other objects. True, a larger planetoid is going to have a much easier time of doing this than a smaller planetoid, but theoretically you could have a Jupiter-sized "dwarf planet" in the same solar system as a Pluto-sized "planet."

Re:Not to be pendantic, but... (1)

Randle_Revar (229304) | about 2 years ago | (#39603519)

>Exoplanets are not a subset of planets, they are a different class of objects altogether.

Troll harder

Here comes wads of funding! (1)

Cazekiel (1417893) | about 2 years ago | (#39603057)

Now you KNOW there's gonna be a jump-start in the government throwing big bucks into NASA. If they did it during the Communist vs. Capitalist dick-waving that went on for decades, how are they going to tolerate the idea that there are other planets out there, ones that MIGHT get to other exoplanets first? The fear, anger, propaganda... I can see Obama now...

"By 2419, we will send a man to 51 Pegasi b!"

It'd be better in a Boston accent, but hey, let's get our light-speed on!

Cannot claim any of them as planets (1)

SnarfQuest (469614) | about 2 years ago | (#39603173)

In order for something to be called a planet, it must obet the following rules, according to WikiPedia [wikipedia.org] .

1 is in orbit around the Sun,
2 has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3 has "cleared the neighbourhood" around its orbit.

They fail #1 (they aren't orbiting the Sun, but some other star), they cannot prove #2 (could be a bunch of disk-worlds), and they haven't proved #3.

Thus, none of these can clearly be claimed that they are planets.

Re:Cannot claim any of them as planets (1)

Surt (22457) | about 2 years ago | (#39603461)

That's the IAU definition. They are not planetary experts, and should not be consulted when constructing a planetary definition.

More Great Work from Kepler (3, Informative)

physburn (1095481) | about 2 years ago | (#39603387)

NASA's Kepler mission has so far found 2300 potential planets outside the solar system, and the mission has been extended to past 2016. Way to go Kepler!

---

Extra Solar Planets [feeddistiller.com] Feed @ Feed Distiller [feeddistiller.com]

Not necessarily planets (0)

Anonymous Coward | about 2 years ago | (#39603771)

Thanks to the poorly conceived new definition of a "planet", these objects are only planets if they have cleared their orbits. Unfortunately, that's very difficult to determine at this distance. What do we call these things until we determine whether they have cleared their orbits? Stellar satellites, maybe?

Why is this news (0)

Anonymous Coward | about 2 years ago | (#39603859)

Who thought that Sol would have the most planets in the galaxy or the universe? This is like saying that the tree next door has more branches than the tree in our lawn. Well, duh.

All Population I stars have planets (3, Interesting)

symbolset (646467) | about 2 years ago | (#39604185)

Well, they do unless they're binary stars where the planets were so huge they condensed into a star. And the planets go from so close they're in danger of being consumed, to so far out that the the material they would have been made of was flung out of the stellar system instead - in orbits of the maximum closeness that you couldn't fit another planetary orbit between them. Since every reasonable sized star has a habitable zone, and given the distribution of mass, between 2 and 4 planets have to be in it. Time makes the orbits regular. If the planet in the right spot is too large for Men, it will have a moon of the appropriate size.

This is obvious from the distribution of prestellar masses and the forces that cause stars and planets to form. Who doesn't know this? It's Bode's Law.

See those stars in the sky? They have planets. All of them, near enough as makes no difference. And all of them have planets where liquid water could form. And water is so common that there is water on all of them. And so the Fermi Paradox becomes more intriguing. The stars in the sky where Men cannot live are passing rare - if we can get there.

Let's go already.

Re:All Population I stars have planets (0)

Anonymous Coward | about 2 years ago | (#39607017)

Surely you mean Dermott's law, which is based on a single exponential function, rather than Bode's law, which has an additive term existing solely to adapt it to Sol's first 6 planets? In any case, it's still a pretty lousy prediction. Either our system is not typical to the Population I model you suggest, or the model needs a lot of refinement; AFAICT there's no theoretical basis for an additive term, but I just ran a few quick numbers, and it looks like the best Dermott's Law fit (for Mercury, Venus, Earth, Jupiter, Saturn, Uranus, Neptune) has an error of over least 90% for Mars's orbital period. And it gets worse if you try to fit a "fifth planet" to account for the asteroid belt.

Basically, there's no good law, at least in part because there's at least two distinct effects (material availability for formation, and dynamic stability to stay there) operating simultaneously, and until we see some more solar systems in good detail (i.e. at least enough detail to know we'd have detected at least Venus and Saturn analogues, and everything between), it's not clear whether the too large to be empty, too small for a planet Mars/Jupiter gap is a wild fluke, a near-universal feature pertaining to the transition from terrestrial planets to gas planets, or just an extra-wide gap that occurs with probability ~0.1 between any given adjacent planets (and we just happened to get one between the inner and outer planets, and built a century of explanations on it -- the universe laughs); hell, it's not even 100% clear that the terrestrial-inner, gaseous-outer structure is a common feature.

Certainly, I agree in broad terms, that there seems no obvious effect to make planets avoid the habitable zone, and that the gaps between planets should generally be small enough it's unlikely the whole habitable zone lies in one, but I think before we "go there" (I'm assuming you mean the Alpha Centauri system, which by your logic should have at least one habitable-zone planet around each star, or Barnard's Star, which again "should" have some terrestrial planets, though we know it doesn't have any large gas giants), it's certainly worth pausing a decade or two to get a better picture of what "typical" is in general, and/or make solar gravitational lensing studies of any particular stars of interest, and make sure we've not predicated a mission on theories biased by where we grew up.

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