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> In December 2018, a search for laser light emissions from Tabby's Star was carried out using the Automated Planet Finder (APF), which is sensitive enough to d

> In December 2018, a search for laser light emissions from Tabby's Star was carried out using the Automated Planet Finder (APF), which is sensitive enough to detect a 24 MW laser at this distance. But why? It’s intriguing, I just wish they could say what the hypothesis was. Alien teens goofing off pointing laser pointers on passing flying saucers?

jcims 5y ago
Presumably attempts to communicate with the earth. If we can see them, they can certainly see us.
- throwawayffffas 5y ago
  They almost definitely can't see us. It's 1470 light years away, the light they are seeing now left earth in 650 AD, there wouldn't be much to see, at least assuming the presumed ETs can detect EM transmissions and analyze the earths atmosphere but not directly observe the surface with any appreciable resolution.
  - jcims 5y ago
    The underlying theory behind the SETI interest is that we are seeing the effects of 'alien megastructures' in orbit around that star. If they can build that, presumably they would be able to build scientific instrumentation to characterize the planet if not directly image it.
    - hungryforcodes 5y ago
      I think his point is more that -- given the speed of light -- it's extremely unlikely that there is anything to see from us in...650AD which is what would be arriving there right now.
- Mountain_Skies 5y ago
  Is there any reason for our planetary system to attract attention? It's too far away for our radio transmissions to have attracted attention. Not sure there's anything unusual about us that would warrant attention from a distance.
  - MattPalmer1086 5y ago
    Not necessarily attempts to communicate with Earth. Aliens might be using beamed propulsion for solar sails, for example.
    - mcv 5y ago
      This is probably the only good reason I can think of why they might point a laser directly at us. They have no idea we're here, listening. The chances that we happen to be listening at exactly the right moment is miniscule. For the same reason, I don't have a lot of hope that SETI using radiotelescopes will ever find anything. But using lasers to power a ship or probe headed to our solar system could make sense. Well, maybe not from Tabby's Star; it's over 1000 ly away. I'm sure they have plenty of closer targets to send their probes to.
      - MattPalmer1086 5y ago
        Also just powering craft in their own system, doesn't have to be interstellar targets. See this post for an interesting take on how we could use it in the solar system. https://www.centauri-dreams.org/2022/01/11/interstellar-reach-the-challenge-of-beamed-energy/ https://www.centauri-dreams.org/2022/01/11/interstellar-reac...
        mcv 5y ago
        Yeah, but then what's the likelihood of aiming directly at us? Even a fraction of a degree off and we won't see it.
        MattPalmer1086 5y ago
throwawayffffas 5y ago
I think you are miss-interpreting this. I think they mean it can detect a source of light as small as a 24MW laser. So if there is a planet, or any other object orbiting the star it is very likely to be picked up by this instrument.

jcims 5y ago

Presumably attempts to communicate with the earth. If we can see them, they can certainly see us.

throwawayffffas 5y ago
They almost definitely can't see us. It's 1470 light years away, the light they are seeing now left earth in 650 AD, there wouldn't be much to see, at least assuming the presumed ETs can detect EM transmissions and analyze the earths atmosphere but not directly observe the surface with any appreciable resolution.
- jcims 5y ago
  The underlying theory behind the SETI interest is that we are seeing the effects of 'alien megastructures' in orbit around that star. If they can build that, presumably they would be able to build scientific instrumentation to characterize the planet if not directly image it.
  - hungryforcodes 5y ago
    I think his point is more that -- given the speed of light -- it's extremely unlikely that there is anything to see from us in...650AD which is what would be arriving there right now.
Mountain_Skies 5y ago
Is there any reason for our planetary system to attract attention? It's too far away for our radio transmissions to have attracted attention. Not sure there's anything unusual about us that would warrant attention from a distance.
- MattPalmer1086 5y ago
  Not necessarily attempts to communicate with Earth. Aliens might be using beamed propulsion for solar sails, for example.
  - mcv 5y ago
    This is probably the only good reason I can think of why they might point a laser directly at us. They have no idea we're here, listening. The chances that we happen to be listening at exactly the right moment is miniscule. For the same reason, I don't have a lot of hope that SETI using radiotelescopes will ever find anything. But using lasers to power a ship or probe headed to our solar system could make sense. Well, maybe not from Tabby's Star; it's over 1000 ly away. I'm sure they have plenty of closer targets to send their probes to.
    - MattPalmer1086 5y ago
      Also just powering craft in their own system, doesn't have to be interstellar targets. See this post for an interesting take on how we could use it in the solar system. https://www.centauri-dreams.org/2022/01/11/interstellar-reach-the-challenge-of-beamed-energy/ https://www.centauri-dreams.org/2022/01/11/interstellar-reac...
      - mcv 5y ago
        Yeah, but then what's the likelihood of aiming directly at us? Even a fraction of a degree off and we won't see it.
        MattPalmer1086 5y ago

throwawayffffas 5y ago

I think you are miss-interpreting this. I think they mean it can detect a source of light as small as a 24MW laser. So if there is a planet, or any other object orbiting the star it is very likely to be picked up by this instrument.