<p>Exo-planets are usually observed by small decreases of the outgoing power of the stars accompanying them, when the planet passes between us and the star.</p>
<p>The orbits of the exo-planets lay in one plane. This means that only for a small amount of all possible planes the exo-planets will orbit the star in a way to become visible to us.</p>
<p>On the other hand, this gives the possibility to see more planets around the same star.</p>
<p>How big is, in theory, the portion of all stars that will show a characteristic planet signature? Do the observations agree with this number?</p>
<p>Can observations of exo-planets falsify the assumption that planetary planes are random or alligned. How else could this be verified?</p>
<p>In the second answer to the linked question it is written:</p>
<blockquote>
<p>Thus, approximately 0.011×0.866 =1% of the solar-like stars with planets should show Earth-size transits.</p>
</blockquote>
<p>Does this mean that all orbits are assumed (and observed) to be parallel to the galactic plane?</p>

CC BY-SA 4.0
2021-07-30T15:12:24.760Z
If you are asking whether the planes of the orbits of exoplanets are randomly distributed then I think there is already a question on that somewhere.
ProfRob
CC BY-SA 4.0
2021-07-30T15:25:05.643Z
@ProfRob If we assume random distribution (and one plane orbits) is this confirm by observational data?
Deschele Schilder
CC BY-SA 4.0
2021-07-30T17:43:04.140Z
I rmember recently writing an answer to question about whether all the planetary systems in the galaxy had the same orbital plane, but I can't find that question now.
M. A. Golding
CC BY-SA 4.0
2021-07-30T21:16:19.847Z
@M.A.Golding Have they? Or if not, why not? Are these planes alligned with the galactic plane? Can exo-planet observations confirm or falsify this?
Deschele Schilder
CC BY-SA 4.0
2021-07-30T21:47:28.303Z
See https://astronomy.stackexchange.com/questions/20542/is-there-a-preference-for-orbital-planes-of-planetary-systems-to-be-aligned-with
ProfRob
<observational-astronomy><exoplanet>
What portion of all exo-planets can't be observed?
Deschele Schilder
# What portion of all exo-planets can't be observed?

(Asked by: username_0 on 2021-07-30)

Exo-planets are usually observed by small decreases of the outgoing power of the stars accompanying them, when the planet passes between us and the star.

The orbits of the exo-planets lay in one plane. This means that only for a small amount of all possible planes the exo-planets will orbit the star in a way to become visible to us.

On the other hand, this gives the possibility to see more planets around the same star.

How big is, in theory, the portion of all stars that will show a characteristic planet signature? Do the observations agree with this number?

Can observations of exo-planets falsify the assumption that planetary planes are random or alligned. How else could this be verified?

In the second answer to the linked question it is written:

> Thus, approximately 0.011×0.866 =1% of the solar-like stars with planets should show Earth-size transits.

Does this mean that all orbits are assumed (and observed) to be parallel to the galactic plane?

**Tags:** observational-astronomy, exoplanet

> **Comments:**
> **username_1**: If you are asking whether the planes of the orbits of exoplanets are randomly distributed then I think there is already a question on that somewhere.  
> **username_0**: @username_1 If we assume random distribution (and one plane orbits) is this confirm by observational data?  
> **username_2**: I rmember recently writing an answer to question about whether all the planetary systems in the galaxy had the same orbital plane, but I can't find that question now.  
> **username_0**: @username_2 Have they? Or if not, why not? Are these planes alligned with the galactic plane? Can exo-planet observations confirm or falsify this?  
> **username_1**: See https://astronomy.stackexchange.com/questions/20542/is-there-a-preference-for-orbital-planes-of-planetary-systems-to-be-aligned-with  

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