Author Topic: Boyajians Star Updates And Discussion  (Read 295818 times)

Offline Star One

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Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #161 on: 04/29/2017 03:36 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #162 on: 04/29/2017 04:47 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

Nothing lasts forever. Even our satellites in geostationary orbit will I believe after a million years return to Earth and he's talking about far longer time scales than that.

Offline ChrisWilson68

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Re: Boyajians Star Updates And Discussion
« Reply #163 on: 04/29/2017 04:59 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

I agree.  It seems like there's a lot of evidence against the idea.

A civilization that had expanded throughout the solar system would have been likely to leave noticeable sites on bodies throughout the system, including our moon and other airless bodies without any erosion processes to destroy the evidence, and we should have found it by now.

The only fix I can think of for that is to assume the earlier civilization decided to leave and return our system to a natural state, removing all clear evidence of its existence.  Think of places where we've removed our structures to restore wetlands or other natural habitats.

But then there's still the problem of where the civilization arose.  We arose from a long line of complex organisms that left a rich fossil legacy over hundreds of millions of years.  It's not really plausible that a civilization arose a billion years ago without coming from hundreds of millions of years of complex organisms and there is no record at all that we've found of that.  Are we to believe that they dug up every fossil everywhere on the Earth no matter how deep for a 500 million year period?

They could have arisen from some species in the fossil record after the Cambrian explosion, but then they're relatively recent and it would be hard for them to erase every artifact they ever left.  Imagine trying to find every pot shard and every arrowhead our ancestors left throughout the planet to erase the record of our existence.  And why?  When we restore a natural environment, it's so that natural systems can go back to work, not to try to erase evidence for future archaeologists.

If they didn't arise on Earth but they were indigenous to our Solar System, where did they arise?  If they arose on Mars, we would expect that they arose from hundreds of millions of years of ancestors that left a fossil record, and we've poked around on Mars enough that we would expect to have noticed some of that fossil record by now.  Most other bodies aren't really conducive to evolution of a large, complex life form, except the Earth, Mars, and Venus.

So, Venus seems like the only possibility left.  Maybe Venus was once more friendly to life and it arose, built a civilization, expanded to the solar system, then restored the system to a mostly natural state and left.  It seems unlikely, but not entirely impossible.

Offline ChrisWilson68

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Re: Boyajians Star Updates And Discussion
« Reply #164 on: 04/29/2017 05:02 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

Nothing lasts forever. Even our satellites in geostationary orbit will I believe after a million years return to Earth and he's talking about far longer time scales than that.

But M.E.T. has a point about landing sites on our Moon and similar bodies.  They would be expected to preserve visible evidence for billions of years, unless they happen to be hit by impactors.  If there were multiple landing sites on the Moon, it's unlikely all were destroyed by impacts.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #165 on: 04/29/2017 05:05 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

Nothing lasts forever. Even our satellites in geostationary orbit will I believe after a million years return to Earth and he's talking about far longer time scales than that.

But M.E.T. has a point about landing sites on our Moon and similar bodies.  They would be expected to preserve visible evidence for billions of years, unless they happen to be hit by impactors.  If there were multiple landing sites on the Moon, it's unlikely all were destroyed by impacts.

Just because some natural features on certain bodies can last a long time does not automatically equate to the same being true of complex artificial structures.

Offline ChrisWilson68

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Re: Boyajians Star Updates And Discussion
« Reply #166 on: 04/29/2017 05:53 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

Nothing lasts forever. Even our satellites in geostationary orbit will I believe after a million years return to Earth and he's talking about far longer time scales than that.

But M.E.T. has a point about landing sites on our Moon and similar bodies.  They would be expected to preserve visible evidence for billions of years, unless they happen to be hit by impactors.  If there were multiple landing sites on the Moon, it's unlikely all were destroyed by impacts.

Just because some natural features on certain bodies can last a long time does not automatically equate to the same being true of complex artificial structures.

If the Apollo landings had happened 3 billion years ago, I believe that we would have noticed them with our mapping of the lunar surface.  I see no credible mechanism for their deterioration in a way that would make them not be apparent 3 billion years later, unless they all happened to be hit by large impacts.

None of the mechanisms that would corrode or erode them on Earth apply on the Moon, and the mechanisms that could degrade them on the Moon would not destroy gross features.

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #167 on: 04/29/2017 07:47 pm »
If the Apollo landings had happened 3 billion years ago, I believe that we would have noticed them with our mapping of the lunar surface.  I see no credible mechanism for their deterioration in a way that would make them not be apparent 3 billion years later, unless they all happened to be hit by large impacts.

I'd think that in 3 billion years a large impact nearby would be rather likely to have happened. 3 billion years also a very long time for erosion due to micrometeorite impacts to take place.

Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #168 on: 04/29/2017 09:10 pm »
As much as the idea appeals to me I find it difficult to see how evidence of prior spacefaring civilizations would not be visible in orbit or on moons etc. How long will the US flag on the moon survive? Now imagine entire bases on bodies where almost no erosion occurs.

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?

I agree.  It seems like there's a lot of evidence against the idea.

A civilization that had expanded throughout the solar system would have been likely to leave noticeable sites on bodies throughout the system, including our moon and other airless bodies without any erosion processes to destroy the evidence, and we should have found it by now.

The only fix I can think of for that is to assume the earlier civilization decided to leave and return our system to a natural state, removing all clear evidence of its existence.  Think of places where we've removed our structures to restore wetlands or other natural habitats.

But then there's still the problem of where the civilization arose.  We arose from a long line of complex organisms that left a rich fossil legacy over hundreds of millions of years.  It's not really plausible that a civilization arose a billion years ago without coming from hundreds of millions of years of complex organisms and there is no record at all that we've found of that.  Are we to believe that they dug up every fossil everywhere on the Earth no matter how deep for a 500 million year period?

They could have arisen from some species in the fossil record after the Cambrian explosion, but then they're relatively recent and it would be hard for them to erase every artifact they ever left.  Imagine trying to find every pot shard and every arrowhead our ancestors left throughout the planet to erase the record of our existence.  And why?  When we restore a natural environment, it's so that natural systems can go back to work, not to try to erase evidence for future archaeologists.

If they didn't arise on Earth but they were indigenous to our Solar System, where did they arise?  If they arose on Mars, we would expect that they arose from hundreds of millions of years of ancestors that left a fossil record, and we've poked around on Mars enough that we would expect to have noticed some of that fossil record by now.  Most other bodies aren't really conducive to evolution of a large, complex life form, except the Earth, Mars, and Venus.

So, Venus seems like the only possibility left.  Maybe Venus was once more friendly to life and it arose, built a civilization, expanded to the solar system, then restored the system to a mostly natural state and left.  It seems unlikely, but not entirely impossible.

I agree that Venus is perhaps the most likely candidate where entire cities could have existed say a billion years ago, before being wiped out - perhaps by one of those cataclysmic resurfacing events that was theorized at one stage to have periodically covered the entire surface of Venus in magma. I don't know if that theory still holds, but I think we know little enough about Venus to make the idea of lost civilizations at least plausible.

But it is evidence in space that seems more difficult to get rid off. Unless the civilization was only at the beginning of its space exploration era, perhaps comparable to where we are today. Then evidence could perhaps have vanished, over billions of years. But if they spread throughout the solar system, maybe 500 years further advanced than we are today before being wiped out, well, then I find it difficult to imagine that all such solar system evidence would have vanished.

Offline ChrisWilson68

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Re: Boyajians Star Updates And Discussion
« Reply #169 on: 04/29/2017 09:15 pm »
If the Apollo landings had happened 3 billion years ago, I believe that we would have noticed them with our mapping of the lunar surface.  I see no credible mechanism for their deterioration in a way that would make them not be apparent 3 billion years later, unless they all happened to be hit by large impacts.

I'd think that in 3 billion years a large impact nearby would be rather likely to have happened. 3 billion years also a very long time for erosion due to micrometeorite impacts to take place.

I don't think so.  The vast majority of the surface of the moon is more than 3 billion years old.  Most craters you see today came from the Late Heavy Bombardment that came in the closing stages of the formation of the solar system around 3.8 billion years ago.  And even with all the craters from the LHB, the majority of the surface of the moon is not craters, it's just marked with craters, with non-crater areas between the craters.


Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #170 on: 04/29/2017 11:42 pm »
Folks, this stuff about artifacts in the solar system is far OT from "Boyajians Star Updates And Discussion" I'd suggest a split starting at http://forum.nasaspaceflight.com/index.php?topic=41704.msg1670474#msg1670474

Most craters you see today came from the Late Heavy Bombardment that came in the closing stages of the formation of the solar system around 3.8 billion years ago.
No, most large impact craters date from billions of years ago. Even the youngest areas of the moon are heavily impact gardened once you get down to 10s of meter scales relevant to preserving something like Apollo sites.
« Last Edit: 04/29/2017 11:50 pm by hop »

Offline ChrisWilson68

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Re: Boyajians Star Updates And Discussion
« Reply #171 on: 04/29/2017 11:51 pm »
Folks, this stuff about artifacts in the solar system is far OT from "Boyajians Star Updates And Discussion" I'd suggest a split starting at http://forum.nasaspaceflight.com/index.php?topic=41704.msg1670474#msg1670474

Quote
Most craters you see today came from the Late Heavy Bombardment that came in the closing stages of the formation of the solar system around 3.8 billion years ago.
No, most large impact craters date from billions of years ago. Even the youngest areas of the moon are heavily impact gardened once you get down to 10s of meter scales relevant to preserving something like Apollo sites.

Based on what evidence are you claiming this?

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #172 on: 04/30/2017 04:11 am »
Based on what evidence are you claiming this?
I'm tempted to just go full Jim here, because this is really basic planetary science 101 stuff.... but LRO for example provides direct evidence of the current cratering rate
http://www.nature.com/nature/journal/v538/n7624/full/nature19829.html

Quote
We also observe a secondary cratering process that we estimate churns the top two centimetres of regolith on a timescale of 81,000 years—more than a hundred times faster than previous models estimated from meteoritic impacts (ten million years)

Note even if the old estimate were correct, you are still off by many orders of magnitude.

The timescale to erase the Apollo hardware may be significantly longer than turning over 2cm of regolith, but it's not going to be gigayears.
Quote
And even with all the craters from the LHB, the majority of the surface of the moon is not craters, it's just marked with craters, with non-crater areas between the craters.
The above also shows this is totally incorrect. At meter scales, the surface is basically saturated. All that rolling busted up regolith you see in LROC and surface mission images is craters and ejecta on craters until it all fades into a jumbled mess.

Offline Phil Stooke

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Re: Boyajians Star Updates And Discussion
« Reply #173 on: 04/30/2017 04:31 am »
Hop is quite right about this.  When you look at an LRO NAC image of small craters in an area a few km across, none of them are 3 Gy old.  Imagine a fresh lava flow just emplaced on the Moon.  100 My later it is covered with small craters (say 1 to 10 m across in this area a few km across), and a thin layer of mingled ejecta, a thin regolith.  100 My after that it looks the same, but it's a whole new population of small craters and a thicker regolith.  100 My later it's another whole set of new craters and the regolith is getting thicker again.  Apollo hardware may last a few millions or even tens of millions of years, but it's getting pretty beaten up by then, not to mention spattered with ejecta on and off.  It is not going to last billions of years, that is a common misconception because supposedly 'there is no erosion on the Moon'.  Not true, of course, the lunar surface is constantly being sandblasted by small stuff.  There is a big literature on impact gardening, but as Hop says the new studies speed up the process considerably.  My credentials? I teach planetary image interpretation.

Oops, I guess we are a bit off topic!

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #174 on: 04/30/2017 05:50 am »
Still about erosion rate on the Moon: from http://onlinelibrary.wiley.com/doi/10.1002/2014JE004698/pdf
Quote
Abstract
Landscape evolution on the Moon is dominated by impact cratering in the post-maria period.
In this study, we mapped 800 m to 5 km diameter craters on 30% of the lunar maria and extracted their
topographic profiles from digital terrain models created using the Kaguya Terrain Camera. We then
characterized the degradation of these craters using a topographic diffusion model. Because craters have a
well-understood initial morphometry, these data provide insight into erosion on the Moon and the topographic
diffusivity of the lunar surface as a function of time. The average diffusivity we calculate over the past 3 Ga is
~5.5 m2/Myr. With this diffusivity, after 3 Ga, a 1 km diameter crater is reduced to approximately ~52% of its
initial depth and a 300 m diameter crater is reduced to only ~7% of its initial depth, and craters smaller than
~200–300 m are degraded beyond recognition. Our results also allow estimation of the age of individual
craters on the basis of their degradation state, provide a constraint on the age of mare units, and enable
modeling of how lunar terrain evolves as a function of its topography.

Offline LouScheffer

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Re: Boyajians Star Updates And Discussion
« Reply #175 on: 04/30/2017 05:57 am »

Not to mention artifacts in  orbital space, where preservation is effectively for ever. If a satellite was in geostationary orbit around Venus or Mars, how long would it remain in place? Forever? Or are there mechanisms that will inevitably disturb it?
How about the stuff in heliocentric orbits?   We find 10 meter sized asteroids all the time, presumably billions of years old.  So presumably spacecraft in such orbits could be there for quite a while.  We've even detected suspicious looking objects in such orbits, but projecting back they all seem to intersect the vicinity of the Earth after the beginning of the space age.  So likely they are space junk from our own civilization.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #176 on: 04/30/2017 07:38 am »
Anyway it's verging on the ludicrous to think we can predict what's going to happen to the solar system in the next billion years. Any of a hundred things could happen from a passing star disturbing the Oort cloud causing another bombardment of the inner solar system to a rogue planet or black hole passing through it causing all sorts of disruption. It's impossible to say. I believe on that timescale it's calculated that at some point much sooner than that Mercury's orbit is likely to mean it will clip either Venus or even the Earth. Any of these events could wipe out much evidence that we even existed.
« Last Edit: 04/30/2017 07:40 am by Star One »

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #177 on: 04/30/2017 07:14 pm »
How about the stuff in heliocentric orbits?   We find 10 meter sized asteroids all the time, presumably billions of years old.
The ~10 meter sized asteroids we see are almost certainly not billions of years old. NEAs generally have dynamical lifetimes of a few to perhaps tens of millions of years, and very small asteroids may have even shorter lives for other reasons. The generally accepted picture is that small asteroids are generated in collisions in the main belt, Yarkovsky drifts them into unfavorable resonances with Jupiter, after which they are quickly ejected or smash into something.

The impact rate on small bodies in near earth orbits is also not terribly far off to what the surface of the moon experiences. AFAIK the gravitational enhancement for Earth is only a factor a few, and the Moon is far less.

The outer solar system would be a lot better for long term parking, but anything out there would be a lot harder to detect.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #178 on: 05/01/2017 07:17 pm »
Yet another explanation to explain the odd behaviour of this star.

Is Tabby’s Star Really a Planet Eater?

http://trendintech.com/2017/05/01/is-tabbys-star-really-a-planet-eater/

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #179 on: 05/02/2017 09:24 pm »
April 25, 2017
|
Tabby Boyajian
Hello all,
 
It is a pleasure to announce that as of April 1, 2017, we are now taking photometric data of KIC 8462852 with the LCO 0.4m network thanks to the funds raised by YOU via Kickstarter! We are now paid in full for monitoring our star until June 1, 2018. But that is not all: we still have a couple lose ends to tie up for the project's reimbursements, and I estimate that the remaining funds will cover telescope time until November 30, 2018. What an amazing success!
 
Data are streaming in and we continue to refine our pipeline to improve on the quality and automated routines to identify the next dip. As mentioned in the last report, a sensitive time for us to watch began and the end of February 2017, where an object with a 727 day orbital period would have passed in front of the star and made a drop in light. The 727 days corresponded to the time interval between the two largest dips in the Kepler data at day 792 (18%) and day 1519 (22%). These dips look nothing alike each other, but the idea is that the occulter could be changing shape (for whatever reason) throughout its orbit. Alas, no dip was recovered during this time. However, if we take the same argument and relax the time the second dip occurred, the "sensitive" window remains open for a few more months. We may relax the time the second dip (at day 1519) occurs because it was not alone - it came in a huge complex of dips spanning almost 100 days, where any of these objects could possibly re-enter our line of sight and produce another dip. Another issue with the proposed 727 day orbital period (big dip to big dip) was that we should have seen an additional big dip around day 65 of the Kepler dataset, and we did not (this assumes the 727 day orbital period, and projecting it back in time from the 18% dip that occurred at day 792). Finally, an analysis of historic records reveal a putative dip that occurred October 24 1978, which also fails to match any regularity in the timing of when dips occur.
 
I know what you are thinking - these aren't great guesses to what and when things might happen. But remember, if we could predict anything that the star would be doing, we wouldn't have to be monitoring it like we are now. Knowing when it is and when it is not dipping are important to figuring out what is happening. And from what we have learned of the star so far, it doesn't do what we expect it to do.
 
Another item worth noting is that we just submitted a proposal to look at the star with the Hubble Space Telescope. This is motivated by the fundamental question of where in space (circumstellar or interstellar) the occulting bodies lie. We plan to study this by observing the star in the ultraviolet along with a control star in the same volume of space. The ultraviolet is by far the most sensitive region for assessing absorption along the line of sight, both in terms of individual (gas) absorbers and broad-wavelength (dusty) extinction. We wont learn of the proposal's success (or failure) until sometime this summer after the panel meets for peer review. Hubble time is very competitive (typically a 10-1 shot of acceptance) so fingers crossed!

http://www.wherestheflux.com/single-post/2017/04/25/Your-contributions----observations

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