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No, the models SUGGESTED they existed. Actual proof of the existence of exoplanets was only confirmed relatively recently, and most have been discovered after 2004. . (1988 was the first confirmation, the "official" list is at the Extrasolar Planets Encyclopedia)

This planet was discovered by Lorentz boosting, the theory of which predates Einstein. Meanwhile, 20 exoplanets have been discovered to date using gravitational lensing, an application of General Relativity (a theory created by Einstein ) that was itself first predicted by Einstein. Somehow, the press release (and thus all the subsequent press) failed to mention these "Einstein planets."

This is one of the reasons for the Kepler mission, as it is trying to answer this question in particular. What are the possible variations of planets in the universe (especially the Milky Way galaxy) and just how common are smaller planets, as opposed to gas giants? One of the things that Kepler has discovered is that smaller planets seem to be much, much more common in our galaxy than the larger planets, and that planets which have the rough diameter of the Earth may be found in abundance.

BTW, this is one of the reasons I am against the current definition of a planet by the IAU, because the entire definition seems to be completely ignorant of planets that are outside of our little solar system. Using that definition, the only place that a planet can exist is close to our Sun, and it must have that one unique and only star in the universe as the primary gravitational influence for that body. I guess that hammers home that the 700+ "planets" discovered elsewhere really aren't planets at all. Then again, I have argued that the definition of a planet ought to be based upon the physical characteristics of that body and not upon any heliocentric description. I would even argue that Titan (currently termed a "moon" of Saturn) ought to be "promoted" to the status of a planet in its own right with the Galilean moons being termed dwarf planets along with the Moon. Apparently some astronomers have some problems with that.

Still, with that many planets to sift through, it certainly would be useful to try and come up with some sort of systematic way to classify important characteristics of all of those planets, even if only to find out what kind of characteristics are unusual or even if the Earth is a common or rare kind of planet. Based upon the Kepler data, it may be common, but at the moment we really don't know.

The problem with this thinking is the presumption there is only two data points. There are currently at least 19 different planetary systems with at least three or more planets which can be used for a comparison, and almost everybody involved with extrasolar planets knows this is just the beginning of discoveries. All told, there have been over 700 different planets which have been confirmed outside of our little old Solar System.

I would say that is enough to begin some statistical models and try to come up with some general trends based upon real data besides the single data point of the Sun and its planets. More significantly, this seems to indicate that planetary systems around stars are quite common to the point that stars without planets seem to be an exception... particularly if those stars are solitary stars rather than in systems of multiple stars.

Admittedly we are still mostly blind about what is "out there", but the Kepler survey seems to be providing some real statistical information about how common planetary systems might be, and since so many of the Kepler telescope candidates seem to be found in groups of multiple planets, it seems very likely that one common presumption of planetary formation being in a disc-like structure seems to be holding out very well. What the Kepler survey is really good at doing is identifying candidates which can then be studied with better telescopes now that we know some properties of these particular planetary systems, or even that they exist at all.

Note the previous /. article on the similar topic was about Kepler-22, so I'm thinking this report about Kepler-20 is actually going backwards in time relative to the previous article.

Once again SIMBAD and exoplanet.eu have nothing.

http://exoplanet.eu/star.php?st=Kepler-20

I've looked a bit this morning and can't find anymore info about the star itself. What its apparent magnitude it? What constellation its in? Etc.
All I can figure out is its referred to as Kepler 22 which only makes sense in relation to the program. But I'd love to be able to try and see the star through a telescope.

Go to the exoplanet encyclopedia website instead of a place that headlines "Psychics and Missing Babies -- Dissecting the Blame Game" and "Top Tips from 2011 to Help Earth, Economy: Photos"

http://exoplanet.eu/star.php?st=Kepler-22

Son of a B, e.eu has got nothing. Simbad's got nothing. There is nothing at all other than it exists and there are press releases all over along with fluffy talk about the release. But even the "official record" has nothing. Give it time and it'll get populated. Heck by the time you read this, e.eu might have data.

This is what Kepler-16 looks like on simbad, someday we'll have this level of data for -22

http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Kepler-16

I donno what a simbad is, a friend of mine went around calling it "sinbad" like the sailor for a while. Which is probably a cooler name, at least in the US.

You're right, but even if you reduced the mass of the average star to 1/5 in the ballpark calculation, that would still leave a 20:1 mass ratio between the average star and planet. Also, an average of 10 Jupiter masses for a planet is a somewhat generous figure if you compare it to estimated masses of planets known so far, and observational bias probably skews even those figures towards the larger end.

In the end, it might be a small constant factor here or there, and that wouldn't altogether remove the couple of orders of magnitude of difference. Also, not all visible matter is in stars and planets, so the ratio between total mass in planets and total visible mass in the universe would be even lower than the ratio between planets and stars (although I don't know by what kind of a factor), and since the total mass of dark matter is more than the total mass of visible matter, the proportion of dark matter these planets could make up for is again lower.

On the other hand, I guess it might also be that planets are more frequent than we imagine by a large factor.

Possible planet in the Andromeda galaxy

There's also slight possibility of observation of a planet that's around 3.7 billion light years away.

(we very much distinguish individual stars in some of the nearest galaxies...)

Well It is a good thing that planet hunters are better at finding things than you, seeing as they have found 358 extrasolar planets. From what I hear, it is much harder to observe the wobble of a star's red shift or see the wink of a star as a planet travels between us and it, than it is to break open a rock in a known trilobite bed.

Source http://exoplanet.eu/catalog.php

Although this may be the first Earth-sized exoplanet, 335 exoplanets are already listed in the Extrasolar Planets Encyclopaedia.

Food for thought.

Go to the exoplanets.EU site ; follow the news links to publications about HR 8799 and also see Science for the abstract on Formalhaut (if you're working through a location which pays for access to Science, which I'm not, you should be able to get the paper from there ; there's also Supporting Online Material available, which isn't terribly informative. Now, contrary to SlashDot procedure, I'm going to shut my flap while I RTF-Papers. Shocking, isn't it?

The interesting data is not how many hot Jupiters are found, but how many stars do not have hot Jupiters.

Here's a list of extrasolar planets (last updated in January); and another list. Note the large number of stars that have planets found with mass less than Mj. The converse of that is that those stars do not have planets of mass greater than Mj. The problem, of course, is that negative results are much less published than positive results. However, here is a list of three published papers that listed stars with no planets found (that is, no planets large enough to detect-- which is to say, no hot Jupiters. This list is somewhat out of date, as of 2006.)

So the story is a little incomplete. Some solar systems have hot Jupiters, which in their migration inward disrupt smaller, earthlink planets... but by no means all.

The interesting data is not how many hot Jupiters are found, but how many stars do not have hot Jupiters.

Here's a list of extrasolar planets (last updated in January); and another list. Note the large number of stars that have planets found with mass less than Mj. The converse of that is that those stars do not have planets of mass greater than Mj. The problem, of course, is that negative results are much less published than positive results. However, here is a list of three published papers that listed stars with no planets found (that is, no planets large enough to detect-- which is to say, no hot Jupiters. This list is somewhat out of date, as of 2006.)

So the story is a little incomplete. Some solar systems have hot Jupiters, which in their migration inward disrupt smaller, earthlink planets... but by no means all.

The smallest known exoplanet is the fourth planet of the pulsar B1257+12, with a mass considerably smaller than Earth. Many of the pulsar planets are Earth sized and smaller.

Thanks.

The TVF page was written in 1997, with an update to a table in 2004.

According to this IAU "Working Group on Extrasolar Planets" webpage (http://www.dtm.ciw.edu/boss/planets.html), only a pulsar had a detected planetary system in 1997, with the first 'regular' system detected in 1999 (Ups And).

According to this tracking website (http://exoplanet.eu/catalog.php), ~25 multiple planet systems have now been discovered, of which eight have three or more planets.

While this - likely - isn't enough to do a statistically rigorous test of the TVF's idea, the rate of discovery, and the number and quality of soon-to-be-onstream new projects, suggests that such a test may be possible in less than a decade.

TVF's assessment ("it is difficult to separate out periods for bodies of similar mass that are either close to the same value or are in resonance with one another") is unduly pessimistic ... at the time, 'radial velocity' was the only game in (detection) town; today, microlensing and transits are both proven, and neither is affected by the difficulty TVF mentions.

And a correction: I wrote 'weak lensing'; I should have written 'microlensing'.

http://exoplanet.eu/

My thoughts exactly while I was reading that definition.

It means that, by definition, there are no extra-solar planets. So what the heck are we supposed to call all those things (203 of them, by latest count) smaller than a brown dwarf that we've found orbiting other stars?

It wasn't that long ago (err, wow, 10 years, maybe that's long) that the first extrasolar planet was discovered. I still remember that news announcement I watched on TV...

Anyway, since the discovery of those 3 planets, another planet has been found. Check out the exoplanet encyclopedia (my favourite exoplanets site). It has a catalog with all the data of those planets, some with uncertainty factors. Discovery method, size, catalogue number, the whole lot. Try chucking all that into a spread-sheet, and plot some scatter graphs. Should be a lotta fun. The last time I tried this, it was a bit problematic because the masses are not really known (for planets discovered using spectral shifts), but are merely minimum (maximum?) limits only. But still, an order of magnitude plot could be fun.

Anyway, the 3 planets are already in the catalogue under HD 69830. Don't forget to check out this one as well. Exciting times. I look forward to 200 planets!

It wasn't that long ago (err, wow, 10 years, maybe that's long) that the first extrasolar planet was discovered. I still remember that news announcement I watched on TV...

Anyway, since the discovery of those 3 planets, another planet has been found. Check out the exoplanet encyclopedia (my favourite exoplanets site). It has a catalog with all the data of those planets, some with uncertainty factors. Discovery method, size, catalogue number, the whole lot. Try chucking all that into a spread-sheet, and plot some scatter graphs. Should be a lotta fun. The last time I tried this, it was a bit problematic because the masses are not really known (for planets discovered using spectral shifts), but are merely minimum (maximum?) limits only. But still, an order of magnitude plot could be fun.

Anyway, the 3 planets are already in the catalogue under HD 69830. Don't forget to check out this one as well. Exciting times. I look forward to 200 planets!

It wasn't that long ago (err, wow, 10 years, maybe that's long) that the first extrasolar planet was discovered. I still remember that news announcement I watched on TV...

Anyway, since the discovery of those 3 planets, another planet has been found. Check out the exoplanet encyclopedia (my favourite exoplanets site). It has a catalog with all the data of those planets, some with uncertainty factors. Discovery method, size, catalogue number, the whole lot. Try chucking all that into a spread-sheet, and plot some scatter graphs. Should be a lotta fun. The last time I tried this, it was a bit problematic because the masses are not really known (for planets discovered using spectral shifts), but are merely minimum (maximum?) limits only. But still, an order of magnitude plot could be fun.

Anyway, the 3 planets are already in the catalogue under HD 69830. Don't forget to check out this one as well. Exciting times. I look forward to 200 planets!