KIC 8462852 has faded ~20% in brightness from 1890 to 1989

[Berzerker]

one current theory is Jupiter was dragged closer by gas and dust and then Saturn formed pulling it back away from the sun

an earlier version of the grand tack theory had Jupiter migrating in and out of the asteroid belt ~4.1 bya causing the late heavy bombardment

these theories are trying to explain how we got our water but as our water gets older there's less time to deliver it from the asteroid belt

[Lorizael]

Late Heavy Bombardment was not proposed to explain the origin of the inner planets' water. The theory arose to explain the ages of lunar rock samples. Additionally, Saturn forming is not what pulled Jupiter back in the Nice model, but Jupiter and Saturn entering into a mean-motion resonance.

[Berzerker]

At the end of the paper, Oort conjectured that gravitational interactions with Jupiter could have ejected many minor planets early in the solar system's history, but that part of his analysis is significantly less rigorous than the main argument of the paper. He admits that readily, recognizing that we needed to know more about the orbital elements of the solar system's early history. We do now, thanks in part to modern observations as well as computers powerful enough to run simulations on complicated systems that can't be solved analytically.

Now here's a puzzle, by measuring the ratio of deuterium we might be able to determine where in the solar system comets formed - higher deuterium indicates a more distant, colder origin. Thats one of the reasons why comets have fallen into disfavor as the source for our water, they tend to show higher deuterium rates while asteroids are a much better match for Earth's water.

But it has been suggested we dont really know where comets formed by measuring deuterium ratios because our sample comes mostly from the outer shell of comets, not the inner core. As long term comets travel about they encounter and accumulate water vapors/ices thereby giving us an onion-like structure with varying deuterium ratios reflecting where the ice formed but not the comet itself.

[Donegeal]

Why go right to a possible Dyson Sphere? What about an out going solar sail that is going out on a trajectory approximating one heading in our direction? The farther out from the system, the more it blocks the light. I realize things move (the stars position, our position and a number of other possible details) so I am not suggesting this possible ship is actually coming here, but possibly somewhere that is on a close trajectory to us.

[Ben Kenobi]

Donegal, the problem is the variation. The sail would, provide, pretty much a consistent dimming. Or at least a curve that would indicate some sort of cubic relationship. You'd not see chops up and down. You can even test that yourself at home, with a lightbulb and a sheet of paper.

[Lorizael]

Why go right to a possible Dyson Sphere? What about an out going solar sail that is going out on a trajectory approximating one heading in our direction? The farther out from the system, the more it blocks the light. I realize things move (the stars position, our position and a number of other possible details) so I am not suggesting this possible ship is actually coming here, but possibly somewhere that is on a close trajectory to us.

The closer a solar sail gets to us, the more of the star it blocks, yes. But the closer it gets, the more perfectly aligned with our line of sight to the star it has to be to do any blocking. So it would have to be moving almost directly at us. Additionally, for the brightness to be decreasing at the rate it is, the sail would have to be moving unreasonably fast (although this really depends on the size of the sail, where it starts, etc.).

[The Mad Monk]

INVASION!!! OR WORSE!!!!!

[self biased]

anyone else read Niven's Bowl of Heaven?

[The Mad Monk]

No, was it good?

[pchang]

Yes. It was decent, but felt unfinished. The end was unsatisfying and felt like a set up for sequels.

[The Mad Monk]

Looking at Larry Niven's Catalogue, I realize there are only two books of his could remember reading: The Integral Trees, and A World Out Of Time. This was mainly because of reasons.

Anywho, I remember I picked up AWOOT from the library when I was about ten, because it had Jupiter on the cover and Jupiter was cool and I liked Jupiter a whole lot:



While looking for that image, I found this one:



...and realized that if I had seen a book with that cover, I would never had read AWOOT, and my Larry Niven reading would have been cut almost exactly in half.

Lucky!

[Thoth]

The cause of the dimming should be obvious: Interstellar Chemtrails.