On 30/06/2018 22:58, jacob navia wrote:
Le 28/06/2018 23:13, jacobnavia a écrit :

Accelerating this thing?

And accelerating so fast that we can detect it?

If we are all serious and agree that spaceships do not exist, we will
never see one when it passes by.

A pity for us. Oumuamua is leaving us at great speed. Changing its
course for new endeavours.

jacob

[[Mod. note -- Yes, many of us have read "Rendezvous with Rama".


I didn't, that is one novel from Clarke I am missing. But it is fun now
that it is the VLT that is bringing the news... A much better novel.

Incredible things happen.

If we see another two go past then we will know that ET is a big fan of
Arthur C. Clarke.

But it seems to me that for Oumuamua the "comet-like outgassing"
hypothesis is strongly favored by Occam's razor: we know that other
objects (comets) outgas in this way (many comets are observed to have
non-gravitational accelerations of this type),

Sure, this thing is outgassing. Comets can do it but... we do not see
any outgassing.

Strange isn't it?

It is probably a bit far from the sun now to see if there is any coma.

Why not if this is a comet?

It may be a comet with a nice sturdy thick crust of black sooty dust on
the surface and the heat from the sun has finally reached a volatile
layer deep inside it. The anomolous acceleration isn't really anything
to write home about - merely that it isn't slowing down in exactly the
way that basic gravitational mechanics would predict.

The "comet/inert rock from other solar system just tumbling around"
hypothesis could be true.

But the spaceship hypothesis has some traction in it too.

and if Oumuamua has
spent little time near a star it's quite plausible that its surface
still has plenty of volatiles (e.g., frozen water and/or methane)
which would vaporize (outgas) when heated by a close solar passage.


Sure. But then... we would see it isn't it?

We don't.

And, unlike Rama, Oumuamua's spin (tumbling) period seems to be a
lot longer than 4 minutes.
-- jt]]

ISTR Rama was spinning along the central axis allowing fake gravity on
the inside rim. And they did everything in threes.

[snip]

If it is using the mass of the sun to get a boost, as we do, it is
accelerating in the direction of its next star.

We have just try to figure out where is it moving to.

Fun, isn't it?

What is this thing?


That is an interesting question though. Did the approach trajectory look
planned to take advantage of the position of any of the gas giants to
get a slingshot assist? That *would* favour ET being involved.

--
Regards,
Martin Brown