<p>According to observations by the Kepler space telescope and other ground based observations, it seems that about 5% of the stars in our galaxy have giant gas planets, similar to Jupiter (but often larger). Smaller planets are difficult to detect, but it is estimated that 40% of the stars have small planets orbiting them.</p>

<p>All in all it is said that on average, 1.6 planets are orbiting each star. So almost all stars form a kind of solar system with planets. However, there is still a lot of uncertainty regarding the numbers, since small planets are very, very hard to detect. And other aspects of solar systems, like our asteroid belt, Kuiper belt and Oort cloud are hard to detect even in our own solar system. </p>

<p>But my own opinion is that it is reasonable to assume that we live in a pretty average solar system (because the odds are obviously suggesting this). So I think that almost every star will have a solar system with a couple of planets, some rocky, some gas giants, plus stuff like comets, asteroids and so on.</p>

<p>Source: <a href="http://en.wikipedia.org/w/index.php?title=Extrasolar_planet&amp;oldid=576307814#Proportion_of_stars_with_planets" rel="nofollow">Wikipedia Extrasolar planets</a></p>

CC BY-SA 3.0
2013-10-09T07:40:34.493Z
2013-10-09T07:40:34.493Z
Arne
<p>For many years scientists have studied our own solar system and modern technology allows them to look deeper and deeper into space. Knowing the Sun is only one of a few billion stars in the Milky Way galaxy, I can imagine scientists also started studying other planetary systems… at least enough to know how many planetary systems (like our solar system) reside in our galaxy. </p>

<p>Is there any information available that would be able to (at least "indicate") how many planetary systems reside in our galaxy?</p>

CC BY-SA 3.0
2014-03-05T04:00:15.557Z
I think this should be changed to 'How many star systems are in our galaxy?' There is only one solar system - the system surrounding the sun. That's what solar means.
Beno
CC BY-SA 3.0
2014-03-05T13:44:34.390Z
@Beno Valid point... edited my question to reflect that. Tnx
e-sushi
CC BY-SA 3.0
2014-03-05T13:53:15.773Z
I've edited the question to use "planetary system" instead of "star system", as that seems to be the intent. See Wikipedia for the difference: [Star system](http://en.wikipedia.org/wiki/Star_system) vs. [Planetary system](http://en.wikipedia.org/wiki/Planetary_system). This doesn't affect the answers in any way. It just makes the question more accurate.
called2voyage
CC BY-SA 3.0
2014-03-05T14:05:46.563Z
@called2voyage Even better! Where would we be without smart mods like you? Much appreciated... thanks.
e-sushi
<solar-system><galaxy><milky-way>
How many planetary systems exist in our galaxy?
e-sushi
# How many planetary systems exist in our galaxy?

(Asked by: username_0 on 2013-10-09)

For many years scientists have studied our own solar system and modern technology allows them to look deeper and deeper into space. Knowing the Sun is only one of a few billion stars in the Milky Way galaxy, I can imagine scientists also started studying other planetary systems… at least enough to know how many planetary systems (like our solar system) reside in our galaxy.

Is there any information available that would be able to (at least "indicate") how many planetary systems reside in our galaxy?

**Tags:** solar-system, galaxy, milky-way

> **Comments:**
> **username_1**: I think this should be changed to 'How many star systems are in our galaxy?' There is only one solar system - the system surrounding the sun. That's what solar means.  
> **username_0**: @username_1 Valid point... edited my question to reflect that. Tnx  
> **username_2**: I've edited the question to use "planetary system" instead of "star system", as that seems to be the intent. See Wikipedia for the difference: [Star system](http://en.wikipedia.org/wiki/Star_system) vs. [Planetary system](http://en.wikipedia.org/wiki/Planetary_system). This doesn't affect the answers in any way. It just makes the question more accurate.  
> **username_0**: @username_2 Even better! Where would we be without smart mods like you? Much appreciated... thanks.  

---

## 1 answers

### Answer by username_3 on 2013-10-09. Score: 4

According to observations by the Kepler space telescope and other ground based observations, it seems that about 5% of the stars in our galaxy have giant gas planets, similar to Jupiter (but often larger). Smaller planets are difficult to detect, but it is estimated that 40% of the stars have small planets orbiting them.

All in all it is said that on average, 1.6 planets are orbiting each star. So almost all stars form a kind of solar system with planets. However, there is still a lot of uncertainty regarding the numbers, since small planets are very, very hard to detect. And other aspects of solar systems, like our asteroid belt, Kuiper belt and Oort cloud are hard to detect even in our own solar system.

But my own opinion is that it is reasonable to assume that we live in a pretty average solar system (because the odds are obviously suggesting this). So I think that almost every star will have a solar system with a couple of planets, some rocky, some gas giants, plus stuff like comets, asteroids and so on.

Source: [Wikipedia Extrasolar planets](http://en.wikipedia.org/w/index.php?title=Extrasolar_planet&oldid=576307814#Proportion_of_stars_with_planets)


---

