how many planets do astronomists know of?
537406
in our solar system: 9\n\neven though larger bodies exist in our solar system, we're too used to having 9 planets to ever change.
53486
Well, there's nine so far - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.  However, scientists have discovered other planets that orbit our Sun that are even further out than Pluto!  So there's a possibility that we may update our information involving the solar system sometime in the future....
57853
Actually there is no tenth planet. Although Pluto is an official planet, others objects of about the same size, or even slightly larger won't be officially recognized as planets.\n\nAn object would need to be much larger, say the size of Neptune to become and official 10th planet. And some astronomers think that should an object may be out there.
1049105
Proof, so far there is none, however if you take into account that there are trillions of galaxies each with trillions of stars all of which may potentially have planets, then you have to consider that there is a good chance that there is at least one other planet out there with the potential for life.
375309
Right now there are officially 9 planets. Depending on what we decide in the next year or so that number will change to 8, stay 9, go to 10, or even larger.  \n\nAn object larger than Pluto (2003 UB313) has been found, but we have not granted it official status as a planet. Don't expect this issue to be resolved any time soon, we've more or less "tabled" the issue until our general meeting in August, but there are a number of scientists in the IAU's Division of Planetary Sciences discussing this issue.\n\nRight now the newer astronomy textbooks generally have a section on "the planet controversy," and spend some time talking about all these newly discovered icy bodies.  They are all part of the Kuiper Belt, just like Pluto, and new books seem to be grabbing onto teaching about these objects much like the asteroids, addressing them as the left-overs of the formation of the solar system.  The Cosmic Perspective (a fairly decent intro astro textbook) for example has a chapter on "Remnants of Rock and Ice: Asteroids, Comets and Pluto"
67576
There might be a million planets in space, but not in our solar system...
179092
Speaking in strictly statistical terms, it is inevitable that at any given moment in the life of the universe as a whole there are at least 10 MILLION planets in this galaxy alone which are capable of supporting life.\nIt is statistically a sure bet that at least 10 of these planets are supporting intelligent life.\nStatistics cannot give a clue, however, about what these fellow sapient beings look like or think like.
759202
Ok, how about this:\n\nAstronomers estimate that there are at least 70 sextillion (7×10^22) stars in the known universe. That is 230 billion times as many as the 300 billion in our own Milky Way.\n\n(shamelessly stolen from Wikepedia)
1037220
There are definetly more than nine planetes in the solar system.There are many discovered by scientists and many more are yet to be found. And it is suggested that there are many more solar systems in the milky way.
268549
Yes. Or rather they move across the constellations. The very word "planet" means "wandering star" in ancient greek. The greeks saw that these stars (they didn´t know what they were) were wandering through the constellations and felt they were special. The planets (that can be seen with the naked eye) and the sun move through 13 constellations (not 12 as astrologers think) during the year. \nIn modern astronomy the constellations are just 2 dimensional sectors in the sky used for simple orientation. All in all there are 88 constellations.
691551
The total of extra-solar planets is now up to 193. Two more were discovered just this month.
750080
There are 192 member countries recognized by the United Nations, and 193 recognized by the state department of the U.S. There are currently 9 (the number is disputed) planets if you count Pluto and 8 if you don't, but that is just in our solar system. There are a lot more planets out there.
7302
Do you really mean plants? If so there are quite a few.\nIf you meant planets then most people say 9, although there is a big controversy about what makes something a planet. We have discovered another named Sedna and a couple more that may eventually be called planets.
368130
I'm pretty sure he's referring to 11 main planets in our solar system, not as a whole.\n\nBelieve it or not, many of the predictions made by the Koran have turned out to be true, or at least to a certain extent. It does say that the big bang did happen, it predicts the existance of certain nebulae by their description, and Islamic astronomers were considered to be the best way before the times of of Kepler, for example.\n\nA lot of religions, especially Islam, make predictions based on science. Islam literally loves science and it says that there can be a unity between science and the belief in Allah/God without altering data.\n\nSo yeah, it's entirely possible that there are 11 planets in our solar system. Did we not just discover one hiding around Pluto? \n\nWe always focus on things really far away when sometimes we should stick to our own turf. But yeah, I think the Koran is correct. Right now we're totally sure of 9, I wouldn't be amazed if we found two more hiding around.
171357
Unfortunately we do not have any concrete evidence.  Here is a good quote by the late Carl Sagan:\n\n"There are some hundred billion (1011) galaxies, each with, on the average, a hundred billion stars. In all the galaxies, there are perhaps as many planets as stars, 1011 x 1011 = 1022, ten billion trillion. In the face of such overpowering numbers, what is the likelihood that only one ordinary star, the Sun, is accompanied by an inhabited planet? Why should we, tucked away in some forgotten corner of the Cosmos, be so fortunate? To me, it seems far more likely that the universe is \nbrimming over with life. But we humans do not yet know. We are just beginning our explorations. The only planet we are sure is inhabited is a tiny speck of rock and metal, shining feebly by reflected sunlight, and at this distance utterly lost."
934417
mercury and venus have none\nearth has 1\nmars has 2\njupiter has 60\nsaturn has 31\nuranus has 27\nand neptune has 13.\n\nseeing how pluto has been erased as a planet the moons shouldn't really count, but if you really need to pluto has 3 moons.
15235
It is estimated that there are approximately 200 million stars in the Milky Way and each one has the potential to have a "solar system" of some type.  Depends on many factors and the type of planets that can exist around a particular star also have many factors.  A number of "solar systems" have been found around other stars.  A current list of them can be found at exoplanets.org