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Comment by garmaine | Hacker News Reader

What is interesting about this one is it’s shape, otherwise I don’t think there’s be much interest in such a mission vs waiting for the next one (since there could be as many as 3 a day if our models are correct).

What process other than aliens creates a kilometers long rotating cylinder? It probably IS a natural process, don’t get me wrong, but we haven’t a f$&@ing clue what that might be which makes it really interesting to study.

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Passing at great speed very close to a star? Outer shell or entire thing becomes superheated and malleable. Extreme tidal forces as the object passes the star and gets churned through the high gravity stretch it out. What if it passed close to something super dense, like a black hole, allowing the stresses of tidal force as it whipped around it to melt the rock on their own leaving it to fly away, pulled long and cooling in the cold of dead space.

I don't know how likely such things are, but I don't imagine it takes intelligence to make a long space rock.

To make a long one without breaking it into multiple objects is very unlikely. This thing isn't composed of silly putty -- rocks and metals tend to be brittle and break rather than "stretch out".

Not if they are melted, or softened. It might have taken millions of close orbits around a hot body for that shape to form.

Which also might be why it was ejected and made it to our solar system. The energy in its orbit might have been really high on a close approach to a star and a slight deviation flung it out of that system.

A highly eccentric orbit would have a close approach around a star, and then have it rapidly cool as it traveled away from the star. Repeat millions of times. Would make for a nice orbital, thermal and materials science simulation.

True, but on astronomical scales, unlikely events happen all the time.

The shape doesn’t seem all that incomprehensible to me. Just look at the great variety of rocks we find lying about the Earth. The universe is a big, violent, energetic place, with countless opportunites for rock to be squashed, worn, melted, smashed and congealed into any conceivable shape. I can totally imagine this being a shard ejected from a collision of two larger objects.

As I understand the elongated shape has only been determined based on the light curve. I'm guessing this assumes no big changes in albedo along the surface. It might actually be a much more round object with one light and one dark side. Iapetus is an example of an object with such coloration.

There's also the fact that it seems to be doing a swing-by on the Sun. To pass fairly close to the Earth. But of course, that's why we detected it. Perhaps that are many that we don't detect. Maybe some very fast ones from Sagittarius A* ;)

Given 3-a-year assumption, I wonder what the probability is of one, by chance, getting a gravity boost like that to swing right by earth.

To me, that implies more than three per year. Or real-time targeting.

The cylinder might be interstellar FedEx. It could be completely unmanned and just heading out to some previously surveyed world somewhere to robotically terraform it. This might be a project that could take 100s of years.

Whether by chance or by design, the fact that it has the rough shape of a boat or rocket weakly suggests that it passed through a thicker medium than empty space. But it came through alone; collisions would have fragmented it.

I am an astro-noob. But are you suggesting for example that it might have passed through a gas giant?

Not specially. I imagine a lot of these wanderers of all shapes might exist. Statistically, that we have only seen one with such an unusual shape demands explanation.

One possible reason would be that more conventional shapes are somehow hampered in their travels. My thesis is that a torpedo shape is relatively advantageous to objects traversing a fluid medium. I have no idea what fluid that might be.

Could it be a fragment from a collision of two larger rocky asteroids?

It could be but what collision would output a fragment of this size and shape? Maybe a supermassive one between two large planets

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