Hacker News Reader

Comment by spaceywilly | Hacker News Reader

I think you are confusing “alien” in the sense of “not from our solar system” with the green dudes with big eyes. I think his argument that this meteor (IM1) was not from our solar system is pretty compelling.

It’s not “evidence of aliens,” it’s evidence of extrasolar origin of this particular meteor.

View on HN

As long as he sticks to extrasolar but otherwise normal matter, I don't have a beef. The Oort cloud (as I understand it) is about as close to the edge of Solar you can get before it stops being our local region. Quite why you'd go beyond there, when its a) huge b) essentially uncharted waters and c) perfectly capable of providing novel chemical/isotopic materials in cometary form...

His other news presence went to pretty woo-woo theories fast. Thats the basis of my comment. If he's stopped with the aliens and "Oumuamua had a light sail" nonsense then I'm good.

The sensible non-woo-woo reason is the speeds of the objects and the paths they're following; they don't match things in orbit around the sun, so aren't from the solar system. The Oort cloud reaches out more than half the distance to Alpha Centauri [1], so yes, it's distant for being in orbit around the sun, and there may be all kinds of strange materials out there and elsewhere in the solar system, but those things are not moving like ʻOumuamua. Any talk of aliens is still woo-woo as far as I'm concerned.

[1] https://en.wikipedia.org/wiki/Oort_cloud

But if it's more than halfway to Alpha Centauri, then 1) it shouldn't be gravitationally bound to the sun at all, at least not in the direction of Alpha Centauri, and 2) Alpha Centauri may have its own Oort cloud, which means that this stuff would be continuous from near Sol to near Alpha Centauri.

How strong is the data that the Oort cloud ends at 3 light years? Is it possible that it is just part of the interstellar medium instead?

More than half that distance, but maybe not in that direction? I don't know, that's just what Wikipedia said. Alpha Centauri A and B are each roughly the mass of our sun, so together they should have more pull. Yes, this stuff is continuous (but gets very sparse), and there must be some region where it's temporarily balanced between the stars. It's all quite variable as stars move relative to each other, and the stuff can be taken for a ride on a new star.

Reply on news.ycombinator.com