Could the solar system be teeming with interstellar objects? We'll soon find out (op-ed)

[Admin]

With JWST and other telescopes, we now have the tools to tell the difference between an intelligent visitor and an interstellar 'dark comet' like 'Oumuamua. Let's not get fooled.

Could the solar system be teeming with interstellar objects? We'll soon find out (op-ed) : Read more

 

[Dave]

It has not been proven what Oumuamua actually was. Yes, we have found dark comets and yes these phenomena exist. And yet, nothing has ever behaved or looked or changed speed like Oumuamua. This is an object we no very little about. This is the fault of science it always pretends it has all the answers instead of saying the truth. The truth is there are many phenomena we no nothing about. Science does not have all the answers. We need to investigate and let science prove the facts.

 

[billslugg]

Oumuamua showed a greater than expected acceleration as it left the Solar System. This was due to invisible hydrogen gas emanating from holes in the surface. The hydrogen had been generated over the eons by the dissociation of H2O molecules by cosmic rays and held frozen by interstellar cold.

It was never imaged as more than a point, but its brightness varied regularly by 2.5 magnitudes. Either it was unusually elongated or it had a bright patch, or both. The uncertainty in dimensions could place it within the range of objects already seen in the Solar System.

 

[Dave]

It had an unusual orbit. One perfect for observation. It does not look like a comet at all. If we wanted to observe an intelligent race at some point in our far future without revealing ourselves this would be a a successful way to do so.

 

[Unclear Engineer]

One thing that I wonder about is the certainty that the object is not really part of this solar system. I understand that it passes by the Sun at more than escape velocity for its location in our solar system. But, why could that not be the result of a gravitational "collision" (interaction without physical contact) between that object and another object originally located in the Kuiper Belt or the Ort Cloud? We know that gravitational interactions can eject even large objects from the solar system - why can't the ejection path be initially inward instead of directly outward? After all, we already have used gravitational effects ourselves to propel our Voyager and other probes to more than escape velocity.

 

[billslugg]

Oumuamua could not have obtained its velocity from any known object in the Solar System. We have a complete census of objects big enough to do it within a volume out to 21 AU. Outside that distance, no object in orbit around the Sun has sufficient velocity to do it, by at least an order of magnitude. It might have come from a passing star, though.

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iopscience.iop.org

 

[Unclear Engineer]

Bill, Thanks for the link. Skimming it, I am wondering about the assumption that the orbits of hypothetical objects would be at their circular orbit velocities for their distances from the Sun. IF there is a "planet 9" on a highly elliptical orbit, wouldn't its velocity at perihelion be substantially more than circular velocity at that radius? If it happened to gravitationally collide with another object at perihelion, wouldn't it potentially transfer more velocity than calculated in this paper? And, then there is the potential for the smaller body to have been on a different highly elliptical orbit and having a velocity above its own V-circular at the time of collision.

Just spit-balling, it seems to me that they needed to use the escape velocity at a specific radius for the hypothetical collision in order to logically upper-bound the velocity that something could have by the time it reaches near Earth's orbit from a collision at the far edges of the solar system.

On the other hand, the probability of a real object experiencing an event near that upper limit seems tiny. So, if we see a substantial number of such objects zip by us, it would be very improbable that they came from such improbably gravitational interactions among bound objects, even if it is "possible".

 

[billslugg]

"IF there is a "planet 9" on a highly elliptical orbit, wouldn't its velocity at perihelion be substantially more than circular velocity at that radius?" - UE

Yes, but the escape velocity of all objects outside of 21 AU is not sufficient, it does not matter what their orbit is. Everything massive enough within 21 AU is accounted for.

Oumuamua must have come from another star to a near certain probability. The gap is ten times more velocity than any one Solar System object can give it. It would have had to have many, many encounters, each with a tiny probability.

 

[Dave]

It is our responsibility to know what an object is that comes from outside our star system into our own. A mission from NASA needs to be ready to investigate any phenomena we have little knowledge about. Who knows what other phenomena is out there?