<p><strong>None</strong>. and that doesn't surprise me much.</p>

<p>Comets are thought to be Oort-cloud objects which by interaction either with other Oort-cloud objects or with objects passing the Solar system have been perturbed to venture into the gravitational reach of the outer planets, whence they are
flung into the inner Solar system via close encounters (gravitational slingshots) with one of the outer planets, in particular Jupiter and Saturn. For such a slingshot to be efficient, the encounter must be close when any binary (proto-)comet will most likly be disassociated by the gravitational tides of the sling-shooting planet.</p>

CC BY-SA 3.0
2014-09-05T10:49:09.123Z
Maybe the Oort-clouds are a little bit from the known planets for a slingshot maneuver?
peterh
CC BY-SA 3.0
2014-09-05T17:47:40.170Z
@PeterHorvath see edit.
Walter
CC BY-SA 3.0
2014-09-05T10:05:11.717Z
2014-10-08T19:53:53.620Z
2014-10-08T19:53:53.620Z
Walter
<p>Contact binaries, in which two objects are touching may be fairly common. This is one interpretation of the "rubber duck" shape of the "Rosetta comet" 67P/Churyumov–Gerasimenko, and radar observation of 8P/Tuttle suggest it is also formed of two objects in contact with each other.</p>

<p>The low mass and so weak gravity of comets means that have a very small sphere of influence. It would have a radius of only a few km. </p>

CC BY-SA 3.0
2014-09-06T11:10:45.567Z
2014-09-06T11:10:45.567Z
James K
<p>Many asteroids are today known to be binary, to have "moons".</p>

<p>But what <strong>comets</strong> are known to be binary? Or what fraction of them are theoretically thought to be binary? And if possible, then separate Oort cloud comets from comets with more local asteroid like orbits in this respect.</p>

CC BY-SA 3.0
2014-08-10T15:57:15.890Z
This article explores one of them (http://science.nasa.gov/science-news/science-at-nasa/2014/17jul_rosetta/), but it's the only one I can find.
HDE 226868
<comets>
What known comets are binary?
LocalFluff
# What known comets are binary?

(Asked by: username_0 on 2014-07-21)

Many asteroids are today known to be binary, to have "moons".

But what **comets** are known to be binary? Or what fraction of them are theoretically thought to be binary? And if possible, then separate Oort cloud comets from comets with more local asteroid like orbits in this respect.

**Tags:** comets

> **Comments:**
> **username_1**: This article explores one of them (http://science.nasa.gov/science-news/science-at-nasa/2014/17jul_rosetta/), but it's the only one I can find.  

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## 2 answers

### Answer by username_2 on 2014-09-05. Score: 3 | Accepted answer

**None**. and that doesn't surprise me much.

Comets are thought to be Oort-cloud objects which by interaction either with other Oort-cloud objects or with objects passing the Solar system have been perturbed to venture into the gravitational reach of the outer planets, whence they are
flung into the inner Solar system via close encounters (gravitational slingshots) with one of the outer planets, in particular Jupiter and Saturn. For such a slingshot to be efficient, the encounter must be close when any binary (proto-)comet will most likly be disassociated by the gravitational tides of the sling-shooting planet.

> **Comments:**
> **username_3**: Maybe the Oort-clouds are a little bit from the known planets for a slingshot maneuver?  
> **username_2**: @PeterHorvath see edit.  

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### Answer by username_4 on 2014-09-06. Score: 1

Contact binaries, in which two objects are touching may be fairly common. This is one interpretation of the "rubber duck" shape of the "Rosetta comet" 67P/Churyumov–Gerasimenko, and radar observation of 8P/Tuttle suggest it is also formed of two objects in contact with each other.

The low mass and so weak gravity of comets means that have a very small sphere of influence. It would have a radius of only a few km.


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