how many planets are there?

Question

my bf told me a few years ago he read about another little one past pluto???

Answer 1

There are at the latest count 202 planets discovered outside our solar system. There are 20 stars with more than one planet orbiting them

THE ONE WITH MOST PLANETS

55 Cancri A has 4 such planets, simulations suggest that there is a wide stable region between the orbits of planets c and d which could contain additional planets. Models predict that one or more terrestrial planets could form in this gap, though such planets would be undetectable with present-day technology. This is of astrobiological interest since this region includes 55 Cancri A's habitable zone (right temperature, not too much harmful radiation, liquid water would remain stable).

In 2004 a Neptune-mass planet designated 55 Cancri e was announced in a 2.8-day orbit. This planet may either be a small gas giant or a large terrestrial planet.

THE NEAREST ONE TO US

The nearest multiple-planet star is Gliese 876, 15,34 light years away, which has 3 planets, Gliese 876 is a red dwarf star located in the constellation Aquarius. As of 2006 the star is known to host three extrasolar planets, including one with a mass less than half that of Neptune.

Both of the system's Jupiter-mass planets are located in the habitable zone of Gliese 876, which extends between 0.116 to 0.227 AU from the star. This leaves no room for an additional habitable Earth-size planet in the system. On the other hand, large moons of the gas giants, if they exist, may be able to support life

THE MOST RECENTLY DISCOVERED ONE

90% of the planets so far found are gas giants of the size of Jupiter or larger (these are easiest to detect) but the most recently discovered multiple-planet star has 3 Neptune-sized planets the outermost of which is in the habitable zone.

This is HD 69830, a rather inconspicuous nearby orange dwarf star slightly less massive than the Sun. Located 41 light-years away towards the constellation of Puppis (the Stern), It is, with a visual magnitude of 5.95, just visible with the unaided eye. It has an asteroid belt and 3 Neptune-sized planets, the outermost of which is the first known Neptune-mass planet to reside in the habitable zone.

The planets have masses of 10, 12 and 18 times that of Earth, and orbit about the star with periods of about 9, 32 and 197 days, respectively.

Here are the 20 multi-planet stars with distances in light years and Apparent Magnitudes

Upsilon Andromedae A (3 planets) 43.9 light years Magnitude 4.09
HD 12661 (2 planets) 121.2 ly Mag 7,44
HIP 14810 (2 planets) ??
HD 37124 (3 planets) 108.3 ly Mag 7.68
HD 38529 (2 planets) 138 ly Mag 5.94
HD 69830 (3 planets) 41 ly Mag 5.95
HD 73526 (2 planets) 323 ly Mag 9
HD 74156 (2 planets) 210.6 ly Mag 7,62
55 Cancri A (4 planets) 41 ly Mag 5.95
HD 82943 (2 planets) 89.5 ly Mag 6.54
47 Ursae Majoris (2 planets) 45.9 ly Mag 5.03
HD 108874 (2 planets) 223.4 ly Mag 8.76
HD 128311 (2 planets) 54.1 ly Mag 7.48
Mu Arae (3 planets) 49,8 ly Mag 5.12
HD 168443 (2 planets) 123.5 ly Mag 6.92
HD 169830 (2 planets) 118.5 ly Mag 5,91
Gliese 777 A (2 planets) 51.8 ly Mag 5.71
HD 202206 (2 planets) 151.1 ly Mag 8.1
Gliese 876 (3 planets) 15.34 ly Mag 10.2
HD 217107 (2 planets) 64.3 ly Mag 6.17

Of the 148 star with one known planet the nearest is Epsilon Eridani b which is 10.4 light years from earth.

Epsilon Eridani b is a extrasolar planet around Epsilon Eridani, announced in 2000 by a team led by Artie Hatzes. The discoverers gave its mass as 1.2 ± 0.33 times that of Jupiter, with a mean distance of 3.3 AU from the star. The object's orbit is highly eccentric.

Finally the Solar System, The jury is out and there has been a request for a recount, 8-12 is a best guess of the outcome,

Answer 2

technically the International Astronomical Union won't set a defintion for "planet" until 08/24/06
so the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto

they set a draft though: basically everything that is made spherical by gravity that has a diameter of over 800 miles -
which means that Pluto is a planet,
but since Pluto and it's largest moon Charon's barycenter, which is the point which Pluto, Charon, and it's new moons Nix and Hydra orbit around, is in between Pluto and Charon the IAU considers Pluto and Charon a double planet,

so 3 new bodies fit under the definition of planet:
the "minor planet" Ceres, Charon, and one beyond Pluto,
2003 UB213
Pluto, Charon, and 2003 UB213 all being classified a new category: plutons

so there are 12:
Mercury, Venus, Earth, Mars
Ceres
Jupiter, Saturn, Uranus, Neptune
Pluto, Charon, 2003 UB213

there are the 7 potential candidates
so if they include them you get 19

Answer 3

We will likely find out next Thursday when an association of astronomers called the International Astronomical Union votes on the official definition of a planet. The version that is currently up for a vote would add the asteroid Ceres, Pluto's moon/co-planet Charon, and the newly-discovered "Xena" to the list, bringing it up to 12. But who knows what will happen after a week of debate? It should be interesting.

JIM

Answer 4

If you believe the astronomers, at their meeting they just voted that there are 8 classic planets (Pluto is OUT) and 4 more smaller ones (Including Pluto) for a total of 12.

Answer 5

As of officialy today there are 12 planets, including Pluto, Ceres, Charon and Xena. I would still like it if there where only 8, I think pluto should not be a planet, and I don't think Charon should be called a planet.

Answer 6

As I write, there are still nine. However...some astronomers are challenging the definition of Pluto as a planet...and many astronomers are now advocating expanding the definition of a planet, to add as many as 40 more. Yow! Stand by...details at 11....

Answer 7

There are millions of planets in this universe, but scientists can only see 9 so far with our technology, in our solar system. There are also rumours about a blue planet, they saw that they say are capable of having life. But there is still not enough oxygen for lots of humans. (exciting huh?)

Answer 8

yes and no astronomers have recently discovered 3 small planets soon they are going to take a vote on wether or not they should be considered as planets.

Answer 9

There are 76,453 planets in the Galactic Federation. Earth hasn't been invited yet, we are still considered too primitive, dangerous, and backward.

Answer 10

Now they say there are a dozen of planets in our solar system. Go to space.com, and you'll get what I say.