Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Tabby's star is dimming at an incredible rate

sciencealert.com

Post reply on HN
Print view View original

81–90 of 179 posts

Re: Tabby's star is dimming at an incredible rate

#81

Post by erelde »

echelon wrote: post #60
jimmytidey wrote: post #44

Earlier quoted context omitted.

This is an amazing theory. What could possibly be more out there than alien life? Alien life in a gigantic spaceship accidentally coming between you and a star.

Would it be "accidental" if they were traveling in a direct vector approaching us? Incredibly implausible idea for the sheer improbability, but fun to imagine nevertheless.

I would think that by the time they actually move some meaningful distance, their sun would not be 'behind' them anymore, they'd still be moving toward ours, but as the whole thing is constantly moving, their sun would have moved relative to ours.

Re: Tabby's star is dimming at an incredible rate

#82

Post by kuschku »

bitJericho wrote: post #72
api wrote: post #67

Earlier quoted context omitted.

Would it actually be a straight line? Going from e.g. Earth to Mars does not consist of aiming for Mars and firing your rockets. It consists of hitting a parabolic transfer orbit and then doing another burn to place yourself in Mars' orbit -- or just heading right in if you've got the heat shields and retropropulsion for that. Basically you do orbital mechanics like Wayne Gretzky: you don't go to where the planet is,…

The galactic center is 100,000 lightyears away. Going from a location to another 1000 lightyears away via the galactic center would make the trip 200 times longer. A 10,000 year journey would thus take 2 million years. It's probably better to jump from point A to B, then.

no, @api is right - you're orbiting the galactic center for a while.

Similar how transfer from earth to mars works via a solar orbit.

So, yes, you have to include orbital mechanics, not just straight lines.

Re: Tabby's star is dimming at an incredible rate

#84

Post by [deleted] »

fjarlq wrote: post #42
simcop2387 wrote: post #18

Two reddit discussion that might be able to answer some questions we have here: https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper... https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont... They also contain links to the resulting paper itself

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 h…

[deleted]

Re: Tabby's star is dimming at an incredible rate

#85

Post by machrider »

kirykl wrote: post #80
Zardoz84 wrote: post #75

Earlier quoted context omitted.

SETI have some dubious criteria like that an alien civilization would emit at Hydrogen resonance frequency because is a universal constant. Any HAM radio operator or telecommunication engineer know well how bad is trying to emit anything on Hydrogen band because is full of natural noise.

I understand the hydrogen line to be used tho because the noise is constant and any deviation or pattern could be easily identifiable

The problem with noise is that your signal has to be bigger than the noise in order to be intelligible. Preferably you'd find a channel with less noise, not more.

Re: Tabby's star is dimming at an incredible rate

#86

Post by Normal_gaussian »

riffraff wrote: post #56
mjevans wrote: post #34

Earlier quoted context omitted.

From an intelligent life angle, what would really save us is that, aside from a number of planets to observe, we haven't really been all that interesting until the last 100-200 years; when we started actually emitting signs of intelligent life in to space.

Ah, but this is only true about we, humans rather than earth/solar system. It cannot be excluded that other sources of radio have been around here in the past :)

It also assumes that outside observers have the same difficulty understanding the make-up and probable evolution of a system as we do. If they were able to observe that Earth would have some properties they were interested in, or would be a likely candidate for such, then they wouldn't need us to announce our presence to guess it.

Re: Tabby's star is dimming at an incredible rate

#88

Post by c0g »

david-given wrote: post #71
peonicles wrote: post #59

Earlier quoted context omitted.

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…

You just need a big enough ship. A while back I had a plan for a science fiction setting: an inter galactic 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…

Yet another book recommendation: Marrow by Robert Reed. Some similarities to your story :)

Re: Tabby's star is dimming at an incredible rate

#89

Post by [deleted] »

imaginenore wrote: post #46
fjarlq wrote: post #42

Earlier quoted context omitted.

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 h…

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?

[deleted]

Re: Tabby's star is dimming at an incredible rate

#90

Post by ethanbond »

wbl wrote: post #61
ethanbond wrote: post #45

Earlier quoted context omitted.

What causes the soft upper boundary?

The mass of the star before it went and formed a black hole. The bigger a star, the hotter it is, and the more evaporates from the surface, and the shorter it lives. Large blackholes grow through things falling into them.

Oh I read the parent comment as black holes having a soft upper boundary. Is that the case? Or if more stuff falls in they just get bigger (minus Hawking radiation)?
Post reply on HN