Is there any more planets than nine?

Answer 1

It all depends on what your definition of planet is. If this is anything that revolves around the sun, then there are billions, counting even asteroid the size of a grain of sand. If your definition implies a certain minimum mass, then the number of planets depends on what your cut-off mass would be.
There is presently an open debate to decide is Pluto should still be considered a planet, given that it is much smaller than any other, that it orbits the sun in a very odd way (very inclined, with an eccentricity that makes it comes closer to the sun that Neptune at time); especially since an object seemingly larger than Pluto was found further still.

If you decide to consider Pluto and all similar bodies planets as opposed to Kuiper objets, there may be more that remain to be found.

Of course, if you don't limit yourself to our solar system, there should be countless planets around countless stars in countless galaxies.

Answer 2

In this solar system alone, we are starting to find that there could be hundreds of planet sized bodies in the Oort cloud. Some would have orbits lasting thousands of years and be so far from the Sun that it is only a bright star.

In other solar systems we have already found over 200 new planets, and it appears that any star with an Oort cloud might have many hundreds of planets. That would mean that in this galaxy alone we could expect to find over a hundred trillion planets, most of them frozen.

Since we estimate that there are roughly 100 billion galaxies, this means that there might be as many as 1 x 10^25 planets in the universe, maybe more.

Answer 3

The planet, with the current temporary (and unfortunate) name 2003UB313, was discovered in an ongoing survey at Palomar Observatory's Samuel Oschin telescope by astronomers Mike Brown (Caltech), Chad Trujillo (Gemini Observatory), and David Rabinowitz (Yale University).

About the name: The real name of the new planet is currently in limbo while committees decide its fate. For those speculating that the name will be "Lila" based on the web site name I must warn you that that is really just a sentimental dad's early-morning-after-no-sleep naming of a web site for his (at the time) three week old daughter and one should not take it too seriously! In fact, the sentimental dad was so tired he even spelled his own daughter's name wrong (it is "Lilah"). The name "Xena" is frequently heard associated with this planet; this name comes from an internal cod name that we used before we publically announced the existence of the planet. Other code names have been "Santa" (2003 EL61), "Rudolph" (the moon of 2003 EL61), "Easterbunny" (2005 FY9) and "Flying Dutchman" (Sedna), and "Gabrielle" (the moon of 2003 UB313). We use these names internally simply because they are easier to say and remember than things like 2003 EL61 or S/2005 (2003 UB313) 1 . There is no chance whatsoever that these will become the permanent names of these objects! As soon as the committees make their decisions these objects will get real names. When we first announced the existence of these objects we thought that the real names would be decided in days to weeks, not months to years so it never occured to us that these code names would last more than a few days. We hope the committees decide soon so people can start getting used to the real more dignified names soon!
What is it?

This new planet is the largest object found in orbit around the sun since the discovery of Neptune and its moon Triton in 1846. It is larger than Pluto, discovered in 1930. Like Pluto, the new planet is a member of the Kuiper belt, a swarm of icy bodies beyond Neptune in orbit around the sun. Until this discovery Pluto was frequently described as "the largest Kuiper belt object" in addition to being called a planet. Pluto is now the second largest Kuiper belt object, while this is the largest currently known.


Where is it?

The new planet is the most distant object ever seen in orbit around the sun, even more distant than Sedna, the planetoid discovered almost 2 years ago. It is almost 10 billion miles from the sun and more than 3 times more distant than the next closest planet, Pluto and takes more than twice as long to orbit the sun as Pluto.

The orbit of the new planet is even more eccentric than that of Pluto. Pluto moves from 30 to 50 times the sun-earth distance over its 250 year orbit, while the new planet moves from 38 to 97 times the sun-earth distance over its 560 year orbit.



How big is it?

Usually when we first discover distant objects in the outer solar system we don't know for sure how large they are. Why not? Because all we see is a dot of light, like the picture at the top of the page. This dot of light is sunlight reflected off the surface of the planet (interestingly the sunlight takes almost a day to get out to the planet, reflect off of it, and get back to the earth!), but we don't know if the object is bright because it is large or if it is bright because it is highly reflective or both.

When an object is too far away to directly see how big it is, astronomers use an indirect method instead where they measure the heat coming from the object. If we wanted to measure the size of a fire, for example, we could do it by measuring the total amount of heat coming from the fire. The temperature of the flames in a match and a bonfire are essentially the same, but a bonfire emits much more heat because it is much bigger. The same is true of distant planets. Because we know how far away the planet is we have a pretty good idea of the surface temperature (a frosty 405 degrees below zero!), thus when we measure the total heat we can tell how big the object is. Unfortunately, the new planet is so far away and so cold that our first attempt at measuring the heat, using the Spitzer Space Telescope, could not detect the heat output. This fact tells us that the object must be smaller than about 3300 km.

In the meantime, observations have been made by a group from the University of Bonn from the 30-meter IRAM telescope. This telescope, like Spitzer, measures the heat output. IRAM measures the heat output in a region of the spectrum where much less heat is given off, but IRAM is a much larger telescope than Spitzer. The observations were successful in finally detecting the heat of 2003 UB313. From the amount of heat measured they determined that 2003 UB313 has a diameter of 3000 +/- 400 km. A very nice discussion of the measurement and what the uncertainties mean can be found at the press release web page.

The newest size measurement comes from the Hubble Space Telescope. While for most telescopes the planet is too small to be seen as anything other than a dot of light, HST can (just barely) directly measure how big across it is. The measurement is extremely hard, however, even for HST, because even HST distorts light a little bit as it goes through the telescope, and we needed to be sure that we were measuring the actual size of the planet, rather than being fooled by distortion. So we waited until the planet was very close to a star and then snapped a series of 28 pictures and carefully went back and forth comparing the star and the planet. In the end, we determined that the planet is 2400 +/- 100 km across.

Answer 4

There are probably many millions of planets. In our system there are eight confirmed planets. They still argue about whether or not Pluto is really a planet and they recently found a new planetary object. If they confirm that Pluto is a planet then this one would undoubtedly be called one as well. Then the thought becomes that there are many more similar rocks out in the Oort Cloud that will be referred to as planets.

Answer 5

Scientists have recently discovered a new planet beyond Pluto in our galaxy, tentatively calling it "Planet X" - it's a pretty amazing thing.

So, although we were all taught growing up that there are 9 planets in our solar system, there appear now to actually be 10!

Answer 6

They (scientists) are deciding on what the definition of a planet is NOW, they will present the answer at the end of this year. This way they will be able to clear up the "question" of Pluto.

But, yes, to answer your question, they believe there are now 10 planets. The newest one being beyond Pluto.

http://www.signonsandiego.com/news/science/20050730-0338-newplanet.html

Answer 7

Whats the definition of a planet?

Answer 8

Yes! No one except God knows how many are out there. Remember, planet earth is in one galaxy and there are many galaxies out in the heavens.

Answer 9

yeah... the 10th is Sedna... and the 11th is Quaoar (which is a totally awesome name)

Answer 10

OH YES!! they are endless!!! IS that not wonderful!!!???