5 ms·

Relative to planet #9 we're right next to a giant nuclear fusion powered light 700,000 km across. If it isn't lighting up the surface of planet #9 well enough f

by avar 8y ago

Relative to planet #9 we're right next to a giant nuclear fusion powered light 700,000 km across. If it isn't lighting up the surface of planet #9 well enough for us to see it already, then we're not going to be able to construct some laser that makes a difference. That's before you get to the problem that space is ridiculously big, and sweeping it across the entirety of the surface of the imaginary sphere that might contain planet #9 would probably take millions of years (citation needed).

Rooster61 8y ago
> That's before you get to the problem that space is ridiculously big, and sweeping it across the entirety of the surface of that imaginary sphere would probably take millions of years. The scale isn't lost on me. I'm aware of how much ground would need to be covered when you get out that far, and I figured that might be a pretty damning factor. That said, you wouldn't need to sweep it across the entire surface, only enough of the surface to rule out any interfering debris between us and the object. Wouldn't take much. We would need VERY accurate models of the orbit based on effects on other bodies, but it's hard to totally rule it out in my head.
- snissn 8y ago
  I recently listened to an episode of Sean Carroll's podcast with the planet nine astronomer interviewed. Basically they're working on finding it, but their math can only limit the location of the planet to a specific orbit, and they need to check all possible angles of that orbit and it is a lot of the sky to look through. Edit - podcast link https://www.preposterousuniverse.com/podcast/2018/08/27/episode-11-mike-brown-on-killing-pluto-and-replacing-it-with-planet-9/ https://www.preposterousuniverse.com/podcast/2018/08/27/epis...
  - Rooster61 8y ago
    Damn, you just put a hole in my already utterly impractical scheme. CURSES!!! (twirls mustache) :) In all seriousness, that would definitely kill any possibility. Sweeping an entire orbit at the resolution needed to hit something smaller than Uranus/Neptune would take eons.
    - stcredzero 8y ago
      Space is so hugely, mind-bogglingly big, that even paring it down to small fractions using clever orbital analyses still yields hugely mind-bogglingly big regions of space. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. I think someone should re-imagine all of Star Wars as hard Sci-fi set in the vicinity of a system like Alpha Centauri. That's still a vast setting.
      - masonic 8y ago
        "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." Douglas Adams, The Hitchhiker's Guide to the Galaxy
        stcredzero 8y ago
        Even as old as it is, I didn't think it necessary to explain my reference.
        FlyMoreRockets 8y ago
        I just realized it has been nearly 40 years since I first heard those words on the NPR radio broadcast of "Hitchhiker's Guide to the Galaxy". It was broadcast alternately with the Star Wars radio drama. IIRC, Star Wars was aired Friday nights and Hitchhiker's Guide was Saturday nights. Good times, thanks for the reminder. :)
        wavefunction 8y ago
        You should at least put quotation marks around it.
        stcredzero 8y ago
        It's not an exact quote.
LeifCarrotson 8y ago
Regarding those two points: A very good laser has a beam divergence of tenths of milliradians, or 0.01 degrees. At the radius of planet 9, this is a very large beam, and we'd have a hard time putting out enough power to compete with the sun. Furthermore, the sky has an area of 40,000 square degrees. Our little laser beam projects a circle with an area of 0.0000785 square degrees. You'd need to aim at 500 million spots to see the whole sky.
- avar 8y ago
  > You'd need to aim at 500 million spots to see the whole sky. That's smaller than I expected. To convert that into human scale sqrt(500 million) = 22360, in millimeters that's around 22 meters (72 ft). So if we had a square wall 22 meters by 22 meters we could paint a grid of 1 mm by 1 mm squares on it and end up with around 500 million squares. Then we'd need to stand there in front of the wall with a laser pointer and shine the laser at each individual square and check the light bouncing back at us.
  - hughes 8y ago
    Don't forget - due to the speed of light it takes 5-10 hours to get feedback on if the square illuminated, but maybe more because you don't know exactly how long you'll need to wait. And there's uncertainty in whether your measurement is accurate. And there's a background of other illuminated squares that can interfere with your readings. And you're spinning while this is going on. And the target square is continually moving. You might have just missed it.
- burtonator2011 8y ago
  this has an easy solution. 1. Build a Dyson sphere around the sun. 2. Capture all the mass in the solar system to build a giant freaking laser. 3. Use the energy to from the Dyson sphere to power the laser. 4. Melt your entire civilization.
  - nerfhammer 8y ago
    If it's a super-earth it probably has an iron core. We should be able to use magnets to crash it into the sun. The impact event will be hard to miss. We'll know where it is for sure then. This is a lot less work than building a Dyson sphere.
thaumaturgy 8y ago
For those interested in the notion of using lasers to look at things in space, this XKCD what-if might be helpful: https://what-if.xkcd.com/13/ https://what-if.xkcd.com/13/
- Rooster61 8y ago
  This was actually posted a bit further down in the post. It's a good one though :P
dyukqu 8y ago
Is it my English or is it 1.39 million kilometers across?
- avar 8y ago
  You're right. This was from memory and I'd mixed up radius & diameter. Radius 695,700 km, diameter 1,391,400 km.

by avar 8y ago

Rooster61 8y ago

> That's before you get to the problem that space is ridiculously big, and sweeping it across the entirety of the surface of that imaginary sphere would probably take millions of years. The scale isn't lost on me. I'm aware of how much ground would need to be covered when you get out that far, and I figured that might be a pretty damning factor. That said, you wouldn't need to sweep it across the entire surface, only enough of the surface to rule out any interfering debris between us and the object. Wouldn't take much. We would need VERY accurate models of the orbit based on effects on other bodies, but it's hard to totally rule it out in my head.

snissn 8y ago
I recently listened to an episode of Sean Carroll's podcast with the planet nine astronomer interviewed. Basically they're working on finding it, but their math can only limit the location of the planet to a specific orbit, and they need to check all possible angles of that orbit and it is a lot of the sky to look through. Edit - podcast link https://www.preposterousuniverse.com/podcast/2018/08/27/episode-11-mike-brown-on-killing-pluto-and-replacing-it-with-planet-9/ https://www.preposterousuniverse.com/podcast/2018/08/27/epis...
- Rooster61 8y ago
  Damn, you just put a hole in my already utterly impractical scheme. CURSES!!! (twirls mustache) :) In all seriousness, that would definitely kill any possibility. Sweeping an entire orbit at the resolution needed to hit something smaller than Uranus/Neptune would take eons.
  - stcredzero 8y ago
    Space is so hugely, mind-bogglingly big, that even paring it down to small fractions using clever orbital analyses still yields hugely mind-bogglingly big regions of space. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. I think someone should re-imagine all of Star Wars as hard Sci-fi set in the vicinity of a system like Alpha Centauri. That's still a vast setting.
    - masonic 8y ago
      "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." Douglas Adams, The Hitchhiker's Guide to the Galaxy
      - stcredzero 8y ago
        Even as old as it is, I didn't think it necessary to explain my reference.
        FlyMoreRockets 8y ago
        I just realized it has been nearly 40 years since I first heard those words on the NPR radio broadcast of "Hitchhiker's Guide to the Galaxy". It was broadcast alternately with the Star Wars radio drama. IIRC, Star Wars was aired Friday nights and Hitchhiker's Guide was Saturday nights. Good times, thanks for the reminder. :)
        wavefunction 8y ago
        You should at least put quotation marks around it.
        stcredzero 8y ago
        It's not an exact quote.

LeifCarrotson 8y ago

Regarding those two points: A very good laser has a beam divergence of tenths of milliradians, or 0.01 degrees. At the radius of planet 9, this is a very large beam, and we'd have a hard time putting out enough power to compete with the sun. Furthermore, the sky has an area of 40,000 square degrees. Our little laser beam projects a circle with an area of 0.0000785 square degrees. You'd need to aim at 500 million spots to see the whole sky.

avar 8y ago
> You'd need to aim at 500 million spots to see the whole sky. That's smaller than I expected. To convert that into human scale sqrt(500 million) = 22360, in millimeters that's around 22 meters (72 ft). So if we had a square wall 22 meters by 22 meters we could paint a grid of 1 mm by 1 mm squares on it and end up with around 500 million squares. Then we'd need to stand there in front of the wall with a laser pointer and shine the laser at each individual square and check the light bouncing back at us.
- hughes 8y ago
  Don't forget - due to the speed of light it takes 5-10 hours to get feedback on if the square illuminated, but maybe more because you don't know exactly how long you'll need to wait. And there's uncertainty in whether your measurement is accurate. And there's a background of other illuminated squares that can interfere with your readings. And you're spinning while this is going on. And the target square is continually moving. You might have just missed it.
burtonator2011 8y ago
this has an easy solution. 1. Build a Dyson sphere around the sun. 2. Capture all the mass in the solar system to build a giant freaking laser. 3. Use the energy to from the Dyson sphere to power the laser. 4. Melt your entire civilization.
- nerfhammer 8y ago
  If it's a super-earth it probably has an iron core. We should be able to use magnets to crash it into the sun. The impact event will be hard to miss. We'll know where it is for sure then. This is a lot less work than building a Dyson sphere.

thaumaturgy 8y ago

For those interested in the notion of using lasers to look at things in space, this XKCD what-if might be helpful: https://what-if.xkcd.com/13/ https://what-if.xkcd.com/13/

Rooster61 8y ago
This was actually posted a bit further down in the post. It's a good one though :P

dyukqu 8y ago

Is it my English or is it 1.39 million kilometers across?

avar 8y ago
You're right. This was from memory and I'd mixed up radius & diameter. Radius 695,700 km, diameter 1,391,400 km.