Interstellar Object 'Oumuamua May Be Chunk Of 'Pluto-Like Planet'

Space.com

Scientists studying the interstellar object ‘Oumuamua have proposed that it may be a fragment from a Pluto-like planet beyond our solar system. Researchers from Arizona State University's School of Earth and Space Exploration suggest the object could have originated in another star system, offering new insights into the composition of distant planetary bodies.  Credit: Arizona State University's School of Earth and Space Exploration

Transcript

00:01Well, any astronomer was very interested in this object, including me,

00:05because this was the first time we had confirmed that an object

00:09was coming in from outside of our own solar system.

00:12This was the first thing we ever saw that was not part of our solar system.

00:16There were a few things about Oumuamua that were, you know,

00:19the specific object that were unexpected and unusual.

00:23So initially people thought that it was this very long, like, cigar-shaped object.

00:28So when we saw it, people initially thought that it was an asteroid

00:31because it didn't have a tail, it was just a point of light.

00:36You know, comets have these big, beautiful tails

00:39because they are evaporating lots of gases like water and carbon dioxide.

00:45If we could figure out what unusual circumstances or what circumstances

00:49at the beginning of our solar system might have created an object just like Oumuamua

00:53and give it a natural explanation.

00:56When we had more observations, we found that there was this small rocket effect

01:02like you get for a comet, which was then, okay, how do you match the fact

01:07that it has this comet-like rocket effect but you didn't see the comet tail?

01:12And we settled on the composition of nitrogen ice, frozen ice.

01:16And this was very attractive from the very beginning because this is an ice

01:20that we do see in our own solar system on the surface of Pluto.

01:24So it was, we reasoned it was possible that there could have been Plutos

01:28in other solar systems with nitrogen ice on their surfaces

01:32and a piece of it knocked off could have entered our solar system

01:35and explained everything we saw.

01:37And so then we went through the calculations and the reflectiveness that you need

01:41to exactly reproduce the rocket effect that we observed is the reflectiveness of the surface of Pluto

01:48which has a lot of nitrogen ice on the surface.

01:50So that was like, we hadn't necessarily been expecting that

01:54and it just fell out and I was like, okay, that's amazing. That's great.

01:58Since this fits everything we know about it, it seems reasonable to conclude it is a piece of another planet

02:03and it's a planet like Pluto. That's exciting to have a piece like that in our own backyard.

02:10And more than that, it tells us that the things that happened in our own solar system

02:14where you had Plutos forming and banging into other icy objects and fragments flying off,

02:21all of these things, we learned that that probably did happen in our solar system as a result of this research

02:27and it tells us this is probably a near universal process

02:30and that other solar systems are doing the same thing that our solar system did.

02:34In the process of doing that, just like if you have a bar of soap and you're using it in the shower,

02:39once you've been using it for a long time, you might start off with a fairly chunky bar

02:44but you end up with this annoying little sliver.

02:47And exactly the same kind of thing happens, that if you're just removing layers of material off the surface

02:54then it slowly makes that flattening more extreme.

03:00And so that very naturally also explains why it was so flat when we observed it.

03:07It wasn't that flat when it came into the solar system.

03:10It's just that during the course of going through the solar system,

03:14it lost something like 95% of its mass because it went closer to the sun than Mercury.

03:20And that evaporated so much material that we were just left with the little soap sliver by the time we actually saw it.

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