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Reddit user sigbjoernwilderness's idea is pretty wild... can it be easily ruled out? > Is this the last remaining explanation after Montet/Simon? > The dimmin

by fjarlq 10y ago

Reddit user sigbjoernwilderness's idea is pretty wild... can it be easily ruled out? > Is this the last remaining explanation after Montet/Simon? > The dimming comes from the shadow of a spaceship traveling on an (almost) straight line from KIC8462852 to Earth. The slow continuous dimming results from the increase of the apparent size of the approaching ship while Earth/Kepler is in the penumbra. The irregular dips happen when Kepler accidentally passes the antumbra. A rough estimation by simple geometry would suggest that the alien spaceship is quite big (> 100 km diameter), significantly slower than light velocity (< 0.05 c) and has now almost reached its goal (< 2 ly away), arriving at Earth within the next 100 years after a journey of several 10,000 years. (cf. http://archimedes.soup.io/post/632873371/ http://archimedes.soup.io/post/632873371/) The c200 days of "rapid decreased flux" between Kepler-day 1100 and 1300 (first half of 2012) which Monet/Simon reported, followed by a series of large dips after day 1500, would suggest a course correction with the space ship now on its final homing trajectory. -- Comments? -- https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_montetjoshua_simon_paper/d65t063 https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...

imaginenore 10y ago
How can a ship 100 km in diameter cause any significant dimming of a star, which is 21,980,000 km in diameter? It would have to be pretty close to here and lined up just so perfectly. Why even assume it's a spaceship and not an asteroid or a rogue planet?
- civilian 10y ago
  Because we're brainstorming here! They're not assuming anything. But yes, that's exactly the theory, that the starship is somewhere between us and them, and it sometimes dips into the focal point of light.
- jessaustin 10y ago
  The moon is smaller than the sun, and yet still we have eclipses. It's just a matter of perspective. The object[s] would have to be lined up. That's why an artificial object intentionally traveling to Earth is in some sense more plausible than an asteroid, which could be headed in any direction.
  - vmarsy 10y ago
    Why would it be only one object? It could be a belt of random sizes and shaped asteroids that is between us and the star?
    - Jill_the_Pill 10y ago
      Or the entire Vogon fleet?
- s_kilk 10y ago
  "Ok, one last time... these are small, but the one's out there are far away" - Fr. Ted Crilly https://www.youtube.com/watch?v=dS12p0Zqlt0 https://www.youtube.com/watch?v=dS12p0Zqlt0
- deleted 10y ago
  [deleted]
- ajuc 10y ago
  > Why even assume it's a spaceship and not an asteroid or a rogue planet? Specifity bias. It "feels" more probable to have object going here because someone send it here, than to just have object going here.
whage 10y ago
Do spaceships travel in a straight line? I thought their trajectories are heavily curved in really weird ways due to the garvities of stars and planets around them. Please enlighten me!
- yoodenvranx 10y ago
  I think you overestimate the density of stars in the universe. If I remember correctly there are typically a few lightyears between each star (on average).
  - quantumhobbit 10y ago
    There would still be a curved orbit around the center of the galaxy. That is a bit like arguing that a mission from Earth to Mars would travel in a straight line because there isn't anything in between them.
- manarth 10y ago
  It depends on the frame of reference, which can be somewhat arbitrary. A ship can sail a straight line from Falmouth to Boston, but that motion can be described as an arc because of the curvature of the Earth. Add in the motion of Earth's orbit, and the shape of that motion changes again. Add in the Solar System's motion relative to the Galactic Centre, and it's yet another shape. It's all a matter of perspective :-)
  - ajuc 10y ago
    The straight line from Falmouth to Boston is only straight on a 2d map, because of particular transformation from 3d surface to 2d plane. Nothing to do with reference frame. You indeed can change a curve into a straight line by manipulating the frame of reference, but it would need to be very contrived - basically you follow the object movement and add constant translation and some linear movement on top of that (one example - camera is in on a kite tied to the ship, and the rope is progressively loosened).
peonicles 10y ago
There's a comment [1] in the other reddit thread that somewhat rules this out. > That doesn't even make sense when you're flying within the Solar System. Stuff moves, so you have to fly towards where it's going to be, not where it is. > The star is far enough away to be treated as a point source, with its light forming an apparent cone with the Earth's diameter. It doesn't intuitively make sense, at least to me, that the ship would stay within that cone as it corrects for the motion of our Solar System (and its own) within our galaxy. Remember that this dimming effect has been observable for several decades. Then again, aliens don't have any obligation to make sense to us. [1] : https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper_on_tabbys_star_no_known_or_proposed/d665o6f https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper...
- pygy_ 10y ago
  It could be a way to announce their arrival passively.
  - TheOtherHobbes 10y ago
    That would assume they know we're scanning the skies for short-lived and easy-to-miss flux variations. The corollary: if there are aliens around KIC 8462852 they don't care that what they're doing is visible for 1500 light years around them.
- david-given 10y ago
  You just need a big enough ship. A while back I had a plan for a science fiction setting: an intergalactic ship is approach Earth. The people who sent it thought big, and as a result the ship has at its core an enclosed star (a miniature Dyson Sphere) as a gravitational anchor and power source, and round it is orbiting a vast swarm of asteroids and habitats with a few million times the living space of Earth, inside which civilisations endlessly rise and fall. The plot centred around this thing going to make a class pass by Sol in a few years at 0.01c, with the gravitational effects pretty much dooming the Earth; so the current lead civilisation sends some ships on ahead to evacuate the Earth. (Big ships. I did the maths.) The story never gelled, but I think it's plausible that my ship would produce these effects. BTW, if this turns out to be true, I want credit.
deleted 10y ago
[deleted]
throwaway_yy2Di 10y ago
can it be easily ruled out? Yes: parallax breaks it. If something's colinear with a star today (and occults it), it won't be colinear 6 months later, when the Earth's on the other side of the sun. At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").
- fjarlq 10y ago
  Excellent point... that answers my question. Thanks!
- tzs 10y ago
  If I'm doing that math right, it works out that to not be ruled out by parallax, the object would have to be almost 2 AU in diameter if it was within a few light years of Earth. That seems pretty ridiculous--now we have them not only building a megastructure, but flying it to Earth! However, I wonder if there is a way to save the idea without requiring a ridiculously large spacecraft? Suppose instead of one ginormous ship, it is a fleet of big ships each big enough to cause irregular dimming if that ship happens to get between Earth and KIC8462852. If the fleet is spread out, it could then be that one ship or another ends up between Earth and KIC8462852 at several times during one Earth orbit around the Sun. That would give us the irregular dimming throughout the year. For the slow continuous dimming, perhaps that is something going on with the star itself. That could be what made the inhabitants of the system decide to build a fleet of big ships and leave their weirdly behaving and very scary star.
  - e12e 10y ago
    Maybe the visible size of the ship is bigger, as it's unfolding / building a solar sail to brake using our sun's radiation? (like a parachute on a drag racer). Ah, but 2au is probably still way too big?
    - sitkack 10y ago
      What if the parachute was a big magnetically contained gas cloud ?

by fjarlq 10y ago

imaginenore 10y ago

How can a ship 100 km in diameter cause any significant dimming of a star, which is 21,980,000 km in diameter? It would have to be pretty close to here and lined up just so perfectly. Why even assume it's a spaceship and not an asteroid or a rogue planet?

civilian 10y ago
Because we're brainstorming here! They're not assuming anything. But yes, that's exactly the theory, that the starship is somewhere between us and them, and it sometimes dips into the focal point of light.
jessaustin 10y ago
The moon is smaller than the sun, and yet still we have eclipses. It's just a matter of perspective. The object[s] would have to be lined up. That's why an artificial object intentionally traveling to Earth is in some sense more plausible than an asteroid, which could be headed in any direction.
- vmarsy 10y ago
  Why would it be only one object? It could be a belt of random sizes and shaped asteroids that is between us and the star?
  - Jill_the_Pill 10y ago
    Or the entire Vogon fleet?
s_kilk 10y ago
"Ok, one last time... these are small, but the one's out there are far away" - Fr. Ted Crilly https://www.youtube.com/watch?v=dS12p0Zqlt0 https://www.youtube.com/watch?v=dS12p0Zqlt0
deleted 10y ago
[deleted]
ajuc 10y ago
> Why even assume it's a spaceship and not an asteroid or a rogue planet? Specifity bias. It "feels" more probable to have object going here because someone send it here, than to just have object going here.

whage 10y ago

Do spaceships travel in a straight line? I thought their trajectories are heavily curved in really weird ways due to the garvities of stars and planets around them. Please enlighten me!

yoodenvranx 10y ago
I think you overestimate the density of stars in the universe. If I remember correctly there are typically a few lightyears between each star (on average).
- quantumhobbit 10y ago
  There would still be a curved orbit around the center of the galaxy. That is a bit like arguing that a mission from Earth to Mars would travel in a straight line because there isn't anything in between them.
manarth 10y ago
It depends on the frame of reference, which can be somewhat arbitrary. A ship can sail a straight line from Falmouth to Boston, but that motion can be described as an arc because of the curvature of the Earth. Add in the motion of Earth's orbit, and the shape of that motion changes again. Add in the Solar System's motion relative to the Galactic Centre, and it's yet another shape. It's all a matter of perspective :-)
- ajuc 10y ago
  The straight line from Falmouth to Boston is only straight on a 2d map, because of particular transformation from 3d surface to 2d plane. Nothing to do with reference frame. You indeed can change a curve into a straight line by manipulating the frame of reference, but it would need to be very contrived - basically you follow the object movement and add constant translation and some linear movement on top of that (one example - camera is in on a kite tied to the ship, and the rope is progressively loosened).

peonicles 10y ago

There's a comment [1] in the other reddit thread that somewhat rules this out. > That doesn't even make sense when you're flying within the Solar System. Stuff moves, so you have to fly towards where it's going to be, not where it is. > The star is far enough away to be treated as a point source, with its light forming an apparent cone with the Earth's diameter. It doesn't intuitively make sense, at least to me, that the ship would stay within that cone as it corrects for the motion of our Solar System (and its own) within our galaxy. Remember that this dimming effect has been observable for several decades. Then again, aliens don't have any obligation to make sense to us. [1] : https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper_on_tabbys_star_no_known_or_proposed/d665o6f https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper...

pygy_ 10y ago
It could be a way to announce their arrival passively.
- TheOtherHobbes 10y ago
  That would assume they know we're scanning the skies for short-lived and easy-to-miss flux variations. The corollary: if there are aliens around KIC 8462852 they don't care that what they're doing is visible for 1500 light years around them.
david-given 10y ago
You just need a big enough ship. A while back I had a plan for a science fiction setting: an intergalactic ship is approach Earth. The people who sent it thought big, and as a result the ship has at its core an enclosed star (a miniature Dyson Sphere) as a gravitational anchor and power source, and round it is orbiting a vast swarm of asteroids and habitats with a few million times the living space of Earth, inside which civilisations endlessly rise and fall. The plot centred around this thing going to make a class pass by Sol in a few years at 0.01c, with the gravitational effects pretty much dooming the Earth; so the current lead civilisation sends some ships on ahead to evacuate the Earth. (Big ships. I did the maths.) The story never gelled, but I think it's plausible that my ship would produce these effects. BTW, if this turns out to be true, I want credit.

deleted 10y ago

[deleted]

throwaway_yy2Di 10y ago

can it be easily ruled out? Yes: parallax breaks it. If something's colinear with a star today (and occults it), it won't be colinear 6 months later, when the Earth's on the other side of the sun. At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").

fjarlq 10y ago
Excellent point... that answers my question. Thanks!
tzs 10y ago
If I'm doing that math right, it works out that to not be ruled out by parallax, the object would have to be almost 2 AU in diameter if it was within a few light years of Earth. That seems pretty ridiculous--now we have them not only building a megastructure, but flying it to Earth! However, I wonder if there is a way to save the idea without requiring a ridiculously large spacecraft? Suppose instead of one ginormous ship, it is a fleet of big ships each big enough to cause irregular dimming if that ship happens to get between Earth and KIC8462852. If the fleet is spread out, it could then be that one ship or another ends up between Earth and KIC8462852 at several times during one Earth orbit around the Sun. That would give us the irregular dimming throughout the year. For the slow continuous dimming, perhaps that is something going on with the star itself. That could be what made the inhabitants of the system decide to build a fleet of big ships and leave their weirdly behaving and very scary star.
- e12e 10y ago
  Maybe the visible size of the ship is bigger, as it's unfolding / building a solar sail to brake using our sun's radiation? (like a parachute on a drag racer). Ah, but 2au is probably still way too big?
  - sitkack 10y ago
    What if the parachute was a big magnetically contained gas cloud ?