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Comets Can't Explain Weird 'Alien Megastructure' Star After All (newscientist.com)
schwit1 sends the latest news about KIC 8462852, the star that that led many to learn what a Dyson Sphere is. New Scientist reports: "The weirdest star in the cosmos just got a lot weirder. And yes, it might be aliens. Known as KIC 8462852, or Tabby's star, it has been baffling astronomers for the past few months after a team of researchers noticed its light seemed to be dipping in brightness in bizarre ways. Proposed explanations ranged from a cloud of comets to orbiting 'alien megastructures'. Now an analysis of historical observations reveals the star has been gradually dimming for over a century, leaving everyone scratching their heads as to the cause. Bradley Schaefer of Louisiana State University saw the same century-long dimming in his manual readings, and calculated that it would require 648,000 comets, each 200 kilometres wide, to have passed by the star — completely implausible, he says. 'The comet-family idea was reasonably put forth as the best of the proposals, even while acknowledging that they all were a poor lot,' he says. 'But now we have a refutation of the idea, and indeed, of all published ideas.' 'This presents some trouble for the comet hypothesis,' says Boyajian. 'We need more data through continuous monitoring to figure out what is going on.' What about those alien megastructures? Schafer is unconvinced. 'The alien-megastructure idea runs wrong with my new observations,' he says, as he thinks even advanced aliens wouldn't be able to build something capable of covering a fifth of a star in just a century. What's more, such an object should radiate light absorbed from the star as heat, but the infrared signal from Tabby's star appears normal, he says."
Send quantuum busters, we won't get a Second Chance.
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... he thinks even advanced aliens wouldn't be able to build something capable of covering a fifth of a star in just a century.
Clarke's first law: "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
He doesn't think aliens could be capable of building something to cover a fifth of a star in a century?
Look. Being sincere here, how the pyramids was built is still considered speculation by man, as there's no direct evidence of how they were built.
So right here, on planet Earth, the same types of people - scientists - are incapable of understanding how a large structure the size of the pyramids was built a couple thousand years ago..
Personally, I think these scientists need to understand just because they cannot imagine how something is or could be done, does not mean others cannot and are actually actively doing things well beyond their comprehension...
This star is larger than our Sun, yet it rotates thirty times faster. Its poles are significantly flatter, hotter, and brighter than the rest of the star. Thus a large object could block 22% of the star's light while covering a much smaller percentage of its disk. This also explains why the dips in the light curve are pointed on the bottom, not flat.
There could also be a large unseen planet (i.e. one that does not transit the star from our point of view) pulling on the star's tidal bulge and causing its visible pole to slowly precess away from us. That would explain the gradual dimming.
Roche limit reached about a century and a half ago, breakup continues. A super sized rocky planet which has migrated to within Mercury like distance of it's star and has subsequently been pulled apart. Put the planet in an orbit which is nearly edge on (which it would have to be to be detectable using these methods) and as the debris cloud increases in size the star is progressively dimmed (from our point of view) more and more.
Seems the most obvious explanation.
Interestingly, if you did want make a dyson sphere and you wanted a way to break up some planets to get access to the raw materials then causing them to shift orbits closer to the star might be a way to do it.
Planetary collision, leading to two planets breaking up? There really are all sorts of possible explanations without going straight to dyson sphere builders.
That and that if you're capable of doing this you can't do 20% of a star in 100y time. Look at the advances we've made in computer and building technology, even space tech in the last century and we as a species are just starting. Give us a thousand years at the current rate of progress and if we haven't killed ourselves we can probably strip mine a planet like Mars to build our energy structures.
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The surprise would be if a Class-whatever civilization that's building a Dyson Sphere hadn't already mastered self-assembling, self-replicating construction processes. There should be an exponential increase in the rate over time, if we haven't already missed that window. As the buildbots consume the planets, you just get more buildbots until the number is sufficient. Or if the sphere is to be made of the bots themselves then there's no need for a tail-off. Clarke called 'em monoliths when he had them eat Jupiter, but same idea.
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OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
A "cloud" is not really excluded.
A cloud near the dimming star is excluded, because it'd mean more IR (just like a Dyson sphere would).
However, a cloud might be drifting in midway between earth and this star. The result of that could very well be 20% dimming over 100 years - and no extra IR. No IR because the in-between cloud is too far away from the star to be heated up.
As for the faster irregular variations, it might be 2 or more darker companions stars close to one bright star. The three-body problem is unsolved, and simulations show irregular unpredictable orbits when 3 (or more) stars orbit all with about the same distance from a common center. You could get irregular blinking as the bright star sometimes pass behind one darker companion, and sometimes behind two others.
I know you're joking, but sending nukes to attack a civilization with engineering advanced enough to build a Dyson Sphere or other mega-structures would probably be like ants developing the technology to throw grains of sand at relatively low velocities at us.
A nuke would not be very destructive at all, our sun is 1,300,000 times larger than the earth (so about 11911 times the surface area) a dyson sphere is larger than the star. When they say we have enough nukes to destroy the earth many times over they don't mean blow it into tiny pieces just destroy all life on earth.
Also a structure that size would have to withstand large astronomical objects hitting it from time to time.
if a large 16km asteroid it the earth it would be equivalent to a 200 Million megaton impact(http://www.astronomycafe.net/qadir/q975.html) the biggest nuke ever made is only 50 megatons, that is 4 million times more. Even a 75 meter asteroid has a 100 Megaton impact. Basically if we could send a nuke that far into space the kinetic energy would probably be more than the explosion. And an object that size would be already dealing with things much bigger than a nuke on a regular basis.
also from here http://www.space.com/51-astero... asteroids can reach up to 940 km across, not 16km.