<p>If you don't mind speculation, it seems to me that a massive impact - like the one that is thought to have formed our moon, but even larger, could eject shards like that.    That such a shard could escape it's solar-system and fly through space between solar-systems isn't unreasonable.   Asteroids (to my understanding) are somewhat loosely formed and an elongated shape like that is unlikely.   </p>

<p>A small moon or larger asteroid near a super-nova might get turned into an elongated shape like that by the blast as another speculative answer.   A 3rd possibility might be a ejection from a high velocity and somewhat violent debris disk, perhaps from a planet that fell inside the Roche limit of a white dwarf star. </p>

<p>It's still an object that's strange for two completely separate reasons.  It being the first ever object observed to be passing through our solar-system and it's thought to be very unusual shape (footnote - better images would be nice).   Still, the intersection of two unrelated firsts scores high in statistical improbability, even if the shape can be explained, it still leaves open the question of why two never before seen events coincided with the first ever observed exo-asteroid.</p>

CC BY-SA 3.0
2017-11-27T15:38:08.337Z
2017-11-27T15:38:08.337Z
userLTK
<p>NASA recently discovered <a href="https://www.nasa.gov/feature/solar-system-s-first-interstellar-visitor-dazzles-scientists" rel="nofollow noreferrer">'Oumuamua</a>, an interstellar asteroid that appears to have a very elongated shape, unseen in solar system asteroids.</p>

<p><a href="https://i.sstatic.net/mZzKF.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/mZzKF.jpg" alt="oumuamua"></a></p>

<p>What physical mechanisms, in the progenitor stellar system or from interstellar transit, could lead to the formation of an asteroid with such a shape?</p>

CC BY-SA 3.0
2017-11-20T23:53:47.283Z
Why would it be spherical?
ProfRob
CC BY-SA 3.0
2017-11-20T23:57:47.603Z
No one said anything about sphericity. It is unusually elongated, I.e.it has much higher average axial ratios than asteroids in the solar system
christopherlovell
CC BY-SA 3.0
2017-11-21T07:57:29.373Z
@BenCrowell You can thank [Martin Kornmesser at ESA NASA HEIC](https://en.wikipedia.org/wiki/Martin_Kornmesser) for this dramatic looking image.  Possibly a moment to wheel out the [Flake Equation on xkcd.com](https://xkcd.com/718/).
StephenG - Help Ukraine
CC BY-SA 3.0
2017-11-23T18:27:39.317Z
@BenCrowell It does seem to call to the mind the Arthur C. Clarke , Rama object.
Jeffery Thompson
CC BY-SA 3.0
2017-11-27T15:09:41.310Z
Or an alien practical joke.  They're reading our message boards from afar and snickering at us.   "Best joke played on Earth since the WOW signal".
userLTK
CC BY-SA 3.0
2017-11-27T15:14:42.983Z
@BenCrowell  You're not the only one.   http://www.disclose.tv/news/mainstream_astronomers_now_discussing_the_possibility_that_oumuamua_is_a_spaceship/140898   The good news is, we're due some better imaging from Hubble and Spitzer in the coming months.   That should help clear things up (with a chance of leaving an even bigger puzzle).
userLTK
CC BY-SA 3.0
2017-12-08T18:51:18.113Z
An update from Jason Wright: http://sites.psu.edu/astrowright/2017/11/22/is-1ioumuamua-an-alien-spacecraft/#comment-190611
christopherlovell
<solar-system><asteroids><interstellar-medium><interstellar><oumuamua>
Potential formation mechanisms of the interstellar asteroid 'Oumuamua
christopherlovell
# Potential formation mechanisms of the interstellar asteroid 'Oumuamua

(Asked by: username_0 on 2017-11-20)

NASA recently discovered ['Oumuamua](https://www.nasa.gov/feature/solar-system-s-first-interstellar-visitor-dazzles-scientists), an interstellar asteroid that appears to have a very elongated shape, unseen in solar system asteroids.

[![oumuamua](https://i.sstatic.net/mZzKF.jpg)](https://i.sstatic.net/mZzKF.jpg)

What physical mechanisms, in the progenitor stellar system or from interstellar transit, could lead to the formation of an asteroid with such a shape?

**Tags:** solar-system, asteroids, interstellar-medium, interstellar, oumuamua
> **Comments:**
> **username_1**: Why would it be spherical?  
> **username_0**: No one said anything about sphericity. It is unusually elongated, I.e.it has much higher average axial ratios than asteroids in the solar system  
> **username_2**: @BenCrowell You can thank [Martin Kornmesser at ESA NASA HEIC](https://en.wikipedia.org/wiki/Martin_Kornmesser) for this dramatic looking image.  Possibly a moment to wheel out the [Flake Equation on xkcd.com](https://xkcd.com/718/).  
> **username_3**: @BenCrowell It does seem to call to the mind the Arthur C. Clarke , Rama object.  
> **username_4**: Or an alien practical joke.  They're reading our message boards from afar and snickering at us.   "Best joke played on Earth since the WOW signal".  
> **username_4**: @BenCrowell  You're not the only one.   http://www.disclose.tv/news/mainstream_astronomers_now_discussing_the_possibility_that_oumuamua_is_a_spaceship/140898   The good news is, we're due some better imaging from Hubble and Spitzer in the coming months.   That should help clear things up (with a chance of leaving an even bigger puzzle).  
> **username_0**: An update from Jason Wright: http://sites.psu.edu/astrowright/2017/11/22/is-1ioumuamua-an-alien-spacecraft/#comment-190611  

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## 1 answers

### Answer by username_4 on 2017-11-27. Score: 1

If you don't mind speculation, it seems to me that a massive impact - like the one that is thought to have formed our moon, but even larger, could eject shards like that. That such a shard could escape it's solar-system and fly through space between solar-systems isn't unreasonable. Asteroids (to my understanding) are somewhat loosely formed and an elongated shape like that is unlikely.

A small moon or larger asteroid near a super-nova might get turned into an elongated shape like that by the blast as another speculative answer. A 3rd possibility might be a ejection from a high velocity and somewhat violent debris disk, perhaps from a planet that fell inside the Roche limit of a white dwarf star.

It's still an object that's strange for two completely separate reasons. It being the first ever object observed to be passing through our solar-system and it's thought to be very unusual shape (footnote - better images would be nice). Still, the intersection of two unrelated firsts scores high in statistical improbability, even if the shape can be explained, it still leaves open the question of why two never before seen events coincided with the first ever observed exo-asteroid.


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