Space Engine

Posted: **29 Jan 2020 04:47**

Watsisname wrote:
Source of the post So the more likely explanation is a colder source of dust farther from the star.

I'm not an astronomer, so I don't know if something like this would really be possible, but how about a cloud of dust that was so slowly drifting towards the star that it was caught by the star?
The cloud of dust would, so to speak, wrap around the star.
This could explain the more than 100 year decrease in the brightness of 'KIC 8462852' because more and more dust is accumulating around the star.
The stronger fluctuations in brightness would be explained by denser dust fields within the cloud. Likewise, the more or less regular fluctuations.

Posted: **29 Jan 2020 05:54**

JackDole wrote:
Source of the postI don't know if something like this would really be possible, but how about a cloud of dust that was so slowly drifting towards the star that it was caught by the star?

There are many clouds of interstellar dust out there, but they can't be caught and accumulate around a star like that to explain the long term dimming. Think of interstellar comets -- they come in, swing around the star, and then go right back out into interstellar space. Likewise each individual dust grain falling toward the star would follow a hyperbolic orbit, zooming in and then flying off again. For the dust to be captured over time there must be a lot of collisions between grains, but that would require so many of them that it would dim the star's light by more than just a few percent.

I also think there's a problem for dust clouds getting small and dense enough to explain the very short dips in the light curve that were observed -- sometimes dips of a few percent and then back again in only 10 days. Assuming a cloud falling in at a speedy 100km/s implies it must be less than 1AU across to do that. When interstellar gas and dust clouds get that small, it's because many solar masses worth in a molecular cloud exceeded the Jeans criterion and began to collapse and fragment to form new stars. When clumps get down to less than 1AU in size, they're on the verge of being protostars and are getting very hot.

Posted: **29 Jan 2020 22:22**

Sharpest images ever of the sun (30km resolution)

Wow.

Posted: **29 Jan 2020 23:51**

Wow, indeed! And amazing to compare the solar granulation with a simple desktop experiment of convection cells in rheoscopic fluid.

Posted: **30 Jan 2020 14:28**

Watsisname wrote:
Source of the post with a simple desktop experiment of convection cells in rheoscopic fluid.

It's too bad simulating this tends to be expensive when done right. There are ways to fake it, but fluid dynamics is still too computationally expensive.

Posted: **10 Feb 2020 11:58**

JackDole wrote:
A-L-E-X wrote:
Source of the post Isn't there some weird star out there which seems to show variations that haven't been explained by natural means? I forget its name....

Do you mean 'KIC 8462852' (Tabby's Star)?
Sometimes it gets darker, sometimes brighter, in more or less regular intervals.
(A Dyson's sphere will probably be built there. But it is not yet finished, so these light fluctuations. )
scr00650.jpg

Yes, that one, JD! Have we figured out what is causing the fluctuations yet?

midtskogen wrote wrote:
The universe is big and extremely rare events happen all the time. Consider this: In some star system out there, in some galaxy, two planets are colliding - right now as I type this. And two other planets are also colliding when you read this.

I think it would be extremely interesting if we ever found two planets that shared an atmosphere (or more likely) a planet and a moon that share an atmosphere and if both were habitable we could see the swapping of life back and forth!

Posted: **11 Feb 2020 00:31**

A-L-E-X wrote:
Source of the post Have we figured out what is causing the fluctuations yet?

As far as I know, not yet.

Posted: **11 Feb 2020 07:16**

A-L-E-X wrote:
Source of the post Yes, that one, JD! Have we figured out what is causing the fluctuations yet?

While we don't know the whole story, we can say a lot about what it is and what it isn't. The wavelength-dependence of the dimming shows that it is due to dust, and lack of infrared excess shows that the dust is not at high temperature. So we can rule out alien megastructures, distintegrating planets, and recent violent collisions. It probably has to do with comets or other dust-producing objects or disk farther from the star.

Posted: **12 Feb 2020 02:50**

A-L-E-X wrote:
Source of the post I think it would be extremely interesting if we ever found two planets that shared an atmosphere (or more likely) a planet and a moon that share an atmosphere and if both were habitable we could see the swapping of life back and forth!

Is it even possible, even if we ignore how they could evolve into such a configuration? The bodies would certainly have to be tidally locked, and orbit very close and fast. How to avoid the bodies falling apart, and if they can exchange mass, how maintain a steady orbit?

Posted: **12 Feb 2020 03:08**

midtskogen wrote:
Source of the post Is it even possible, even if we ignore how they could evolve into such a configuration?

Well, at least to some extent Pluto and Charon share some atmosphere apparently. It is a crazy small amount so there is no significant angular momuntum loss and you wouldn't see any spectacular mass transfer as you see in some cataclismic binary stars. Indeed both bodies are tidally locket to each other. But they are not habitable (in the common use of the term).

Posted: **12 Feb 2020 05:45**

A-L-E-X wrote:
Source of the post I think it would be extremely interesting if we ever found two planets that shared an atmosphere (or more likely) a planet and a moon that share an atmosphere and if both were habitable we could see the swapping of life back and forth!

Posted: **12 Feb 2020 10:32**

midtskogen wrote:
A-L-E-X wrote:
Source of the post I think it would be extremely interesting if we ever found two planets that shared an atmosphere (or more likely) a planet and a moon that share an atmosphere and if both were habitable we could see the swapping of life back and forth!

Is it even possible, even if we ignore how they could evolve into such a configuration? The bodies would certainly have to be tidally locked, and orbit very close and fast. How to avoid the bodies falling apart, and if they can exchange mass, how maintain a steady orbit?

I would think the moon would have to be small to lessen tidal forces. The atmosphere at the surface of the planet would have to be rather dense too, which also opens up the question of friction...... so it would have to be near perfect conditions where the distance between them is just enough to thin out the atmosphere between them to make friction negligible. This might be a problem for US2 to solve!

But just using Earth as a model, we have an exosphere that extends outward to about 600 miles from the surface, I believe? How large or small would a satellite have to be to be in a stable orbit at that height without experiencing tidal forces that would tear it apart or friction from the remnants of the atmosphere that would burn it up?

Posted: **12 Feb 2020 10:56**

JackDole wrote:
A-L-E-X wrote:
Source of the post I think it would be extremely interesting if we ever found two planets that shared an atmosphere (or more likely) a planet and a moon that share an atmosphere and if both were habitable we could see the swapping of life back and forth!

scr00672.jpg

JD did you make that or is that already in the program? It looks like two giant eggs dancing around each other haha!

Posted: **13 Feb 2020 00:46**

A-L-E-X wrote:
Source of the post did you make that or is that already in the program?

I made it myself.

Posted: **28 Feb 2020 14:53**

are we going to have these new minimoons just discovered in the program? or will they not be around long enough to warrant that?

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