How many planets does man kind know of?

Question

First right answer gets the points

Answer 1

202 discovered so far orbiting other stars. 14 of those stars have two planets, 5 have three and 55 Cancri has four. The first star to be found with more than one planet was Upsilon Andromeda.

The 202 planets break down as: 47 in multiple planet systems, 148 in single planet systems, 4 orbiting pulsars, 1 orbiting a brown dwarf, and 2 free floating.

The first confirmed detections were finally made in the 1990s. Since 2002, more than twenty have been discovered every year. The numbers have been increasing dramatically recently with a wide range of new techniques being used to find planets:

Astrometry
Radial velocity
Pulsar timing
Transit method
Gravitational microlensing
Circumstellar disks
Direct imaging

Multiple Planet Systems

Upsilon Andromedae A (3 planets)
HD 12661 (2 planets)
HIP 14810 (2 planets)
HD 37124 (3 planets)
HD 38529 (2 planets)
HD 69830 (3 planets)
HD 73526 (2 planets)
HD 74156 (2 planets)
55 Cancri A (4 planets)
HD 82943 (2 planets)
47 Ursae Majoris (2 planets)
HD 108874 (2 planets)
HD 128311 (2 planets)
Mu Arae (3 planets)
HD 168443 (2 planets)
HD 169830 (2 planets)
Gliese 777 A (2 planets)
HD 202206 (2 planets)
Gliese 876 (3 planets)
HD 217107 (2 planets)

As regards this solar system, I suppose the best answer at this moment is 8-12, as Pluto may be downgraded from planetary status and Xena Ceres and Charon may be upgraded to that status at a September meeting of the International Astronomical Union.

Answer 2

The nine you know of plus the new lineup would include 2003 UB313, the farthest-known object in the solar system and nicknamed Xena; Pluto's largest moon, Charon; and the asteroid Ceres, which was a planet in the 1800s before it got demoted. This will make 12.

This is from discovery magazine Nov 2004:

I'll start with Pluto so you'll have something to go by. Pluto is 3.7 billion miles from the sun, Diameter is 1,430 miles, Orbital period is 249 years.

Sedna discovered 2003, Ranges from 7 billion to 90 billion miles from the sun, Diameter is 600 - 1100 miles, Orbital period is 10,500 years, Coldest body in the solar system at -400 F.

Ixion discovered 2001, Distance from sun 3.7 billion miles, Diameter 500 miles, Orbital period 250 years.

Quaoar discovered 2002, Distance from sun 4 billion miles, Diameter is 800 miles, Orbital period is 285 years.

UX25 discovered 2002, Distance from sun 4 billion miles, Diameter 580 miles, Orbital period 278 years.

Varuna discovered 2000, Distance from sun 4 billion miles, Diameter 560 miles, Orbital period 283 years, Says its probably a pile of rubble.

TX300 discovered 2002, 4 billion miles from sun, Diameter 540 miles, Orbital period 283 years.

AW197 discovered 2002, Distance from sun 4.4 billion miles, Diameter 550 miles, Orbital period 327 years.

DW discovered 2004, Distance from sun 4.4 billion miles, Diameter 1000 miles, Orbital period 250 years.

Here are a few more:

UB313,
HD187123,
Tau Bootis,
HD 75289,
51 Pegasi,
Upsilon Andromedae (b),
Upsilon Andromedae (c),
Upsilon Andromedae (d),
HD 217107,
Rho1 55 Cancri,
Gliese 86,
HD 195019,
Rho Corona Borealis,
HD 168443,
Gliese 876,
HD114762,
70 Virginis,
HD 210277,
16 Cygni B,
47 Ursae Majoris,
Herculis

Alot of these could become planets pretty soon also. I didn't know Charon was Pluto's moon, I don't think that would be right to make Pluto's moon a planet. Also Ceres is a asteroid, there are bigger thing's out there that would make a better planet than a moon and a asteroid. I like Sedna because it is such a crazy planet going all the way out to the Oort Cloud and back.

Answer 3

202 known extrasolar planets + the new 12 planet solar system = 214

In case you're wondering about the 12 planet solar system, scientists are redefining what constitutes a planet. The vote is on August 24.

The three new planets would be :
Ceres, which was an asteroid before the change,
Charon (Pluto's moon),
And "2003 UB313", a ball of ice a bit bigger than Pluto and even further away from the Sun. It will probably be given a proper name soon.
http://today.reuters.com/news/articlenews.aspx?type=topNews&storyID=2006-08-16T182712Z_01_L16224965_RTRUKOC_0_US-SCIENCE-PLUTO.xml&archived=False

Answer 4

Depends on you define planet, which lately seems that the consensus is only 8 in our solar system, but there are many more in other star systems.

Experiments starting in the 90s proved there were planets around other stars, and I believe 100s have been discovered, though we know little about them because of their great distance from here.

Answer 5

I say 8, since it seems Pluto and Charon are in question. And I certainly don't think Ceres is a planet, even though it's round. I think the definition of 'planet' has to include some sort of size, since there a lot of very small, round objects that orbit the sun.

Answer 6

In our solar system are 9 planets today. Any change hasn't been approved yet (though it probably will be changed next Thursday).

And there are of course some two hundred planets outside our solar system, and the number is increasing.

Answer 7

Like what they say, 8, 9 or 57 known planets.

Answer 8

A planet is any material body that orbits a star (generally in its own orbit, which disqualifies asteroid belts). We've found up to 50 orbiting our sun, and hundreds have been discovered orbiting other stars.

Answer 9

9, possibly 10 (2003-UB313)

http://science.nasa.gov/headlines/y2005/29jul_planetx.htm?list165102

Answer 10

nine!