[Ciara2000]

How many planets are in space

[excon]

Hello C:

We don't know yet. We're still finding 'em.

excon

[ebaines]

In our own solar system there are 8 major planets and 5 dwarf planets (Pluto, Ceres, Eris, Haumea and Makemake - see Solar System Exploration: Planets: Dwarf Planets for more info on them). As of June 2010 astronomers have discovered 464 extrasolar planets revolving around other stars, and more are being discovered all the time.

[asking]

Astronomers have counted 466 planets outside the solar system so far.

There must be many, many times that many in the universe.

[kryostar]

I read in national geographic that there are more stars and planets than there are grains of sand in all of earths oceans

[tkrussell]

Interesting piece of information,

I read in national geographic that there are more stars and planets than there are grains of sand in all of earths oceans

However, the question specifically only asks about planets, not stars.

[asking]

Astronomers have counted 466 planets outside the solar system so far.

There must be many, many times that many in the universe.

Edit: As of July 28, 2010, 473.

[excon]

Hello again, asking:

Wow. Two more in just a few days... There must be zillions of 'em.

excon

[kryostar]

We have counted so few because they are so hard to see, but it stands to reason that most all stars have left over debris forming planets orbiting around them

[zerotiger]

Well there are over 2 billion stars in our galaxy alone. And trillions of trillions of galaxies in the universe. Most of the stars do not likely have planets orbiting them. If even 1% of all stars in the universe have at least 1 planet, we're talking about trillions and trillions of planets in the univers.

[asking]

December 31, 2010

We are up to 516 planets. I bet the astronomers will find lots more in 2011.

Happy New Year!

[Capuchin]

And now you can help.

http://www.planethunters.org/ is a scientific setup that believes that humans are better at categorising data than a computer can be, so they want you to analyse data to look for extra-solar planets!

These are the same people that setup galaxyzoo, a very successful project that characterised over a million galaxies from a sky survey.

They show you the brightness of a star over time, and ask you to identify any patterns in the data - something that the human brain is good at, and something that is very hard to code and cover all variations automatically. There are tutorials to ensure you know what to look for.
Please, if this is something that interests you, this will teach you more about methods we use to detect planets, and you will help us to do real science!

http://www.planethunters.org/