6 ms·

Which stars can see Earth as a transiting exoplanet?

138 points by colinprince 5y ago

lmilcin 5y ago
The best way to search for extraterrestial life I heard is a swarm of drones placed in such a distance from the Sun that it acts as a gravitational lens to greatly magnify any planet around any star in even quite large distance from our system. I think realistic resolutions in kilometers per pixel are theoretically possible even with existing technology (assuming we can build the swarm and position it in the right place quite far from the Sun and then maintain communication). The disadvantage is you need many separate fleets of drones to map more than one target.
- shoto_io 5y ago
  Yes. This video explains it rather nicely: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI
- northwest_nfts 5y ago
  Yeah, that sounds similar to the idea of the Terrascope. I think the positioning of drones for the sun might be so wide to be infeasible for the next century. (Like, the drones would have to be in the Kuiper belt) I haven't watched this YT video recently, but I think he also touches on a Sol-scope and a Jupiter-scope https://www.youtube.com/watch?v=jgOTZe07eHA https://www.youtube.com/watch?v=jgOTZe07eHA
  - deleted 5y ago
    [deleted]
pavlov 5y ago
Would Sol look obviously inhabited on the radio spectrum? This is a common sci-fi trope (“Contact”), but I have no idea whether it’s actually true that our radio emissions would be trivially detectable tens of light years away.
- wyldfire 5y ago
  What if they had an array similar to the one used in "Contact" to receive the response?
- fermuch 5y ago
  Our radio waves have traveled for about 200 light years. Proxima centauri, our closest star, is located at 4246 Light years from us. Very, very unlikely that someone can hear us, even if they tried. Space is huge.
  - gpderetta 5y ago
    I think your Alpha Centauri distance is off by 3 orders of magnitude :) Edit: I think there are thousands of stars within 200ly of Earth.
    - _q8zh 5y ago
      Here's an interactive 33ly radius model: https://gruze.org/fly_10pc/ https://gruze.org/fly_10pc/ - left click + drag, mousewheel, right click. Could be more efficient, but this interactive does the trick; shows how loaded our neighborhood is. Going to hamburger menu -> settings -> show labels brings it to a crawl, though filtering objects helps that a bunch. Showing only stars with known planets is rather interesting.
      - BoxOfRain 5y ago
        This is really cool! Definitely going to be a time sink for me!
  - ajakate 5y ago
    Proxima centauri is actually ~4 light years away. Space is really big, but there are a handful of stars in relative vicinity of us (under 250 ly) https://en.wikipedia.org/wiki/Proxima_Centauri https://en.wikipedia.org/wiki/Proxima_Centauri http://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Back/50lys.html http://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Ba...
f00zz 5y ago
Crazy to think that we have catalogued thousands of exoplanets, even though we basically can only detect them if they pass in front of their stars along our line of sight. Space is big, but also pretty crowded.
- Aerroon 5y ago
  I think it's more that we cab tease out a lot of information from very little data by just making some assumptions (physics). This is also why it's so difficult (impossible?) to anonymize personal data - very little of it can lead to understanding who you are. It is remarkable what astronomers/physicists have achieved though.
- holoduke 5y ago
  And probably there are more roque planets than planets with a star. Those are even harder to detect.
bulatb 5y ago
Event Horizon recently interviewed Lisa Kaltenegger (coauthor here) and Jackie Faherty about a similar paper they wrote: "Past, present and future stars that can see Earth as a transiting exoplanet." https://www.youtube.com/watch?v=W5CV6exdqcg&t=1m56s https://www.youtube.com/watch?v=W5CV6exdqcg&t=1m56s
dekhn 5y ago
People who are interested in learning more about transmitting information between solar systems should watch this wonderful talk: https://www.youtube.com/watch?v=sImBlq542TQ https://www.youtube.com/watch?v=sImBlq542TQ the author is a professor at harvard (known for writing 'The Art of Electronics' in addition to searching for extraterristrials) and put a lot of good thought into light transfer between solar systems. TL;DR a powerful enough laser that is well collimated would work.
Kattywumpus 5y ago
Aliens Can Watch ‘I Love Lucy’: https://www.lscheffer.com/tv.pdf https://www.lscheffer.com/tv.pdf
seventytwo 5y ago
What a fantastic question! I hope to see more of this kind of thing

138 points by colinprince 5y ago

The best way to search for extraterrestial life I heard is a swarm of drones placed in such a distance from the Sun that it acts as a gravitational lens to greatly magnify any planet around any star in even quite large distance from our system. I think realistic resolutions in kilometers per pixel are theoretically possible even with existing technology (assuming we can build the swarm and position it in the right place quite far from the Sun and then maintain communication). The disadvantage is you need many separate fleets of drones to map more than one target.

shoto_io 5y ago
Yes. This video explains it rather nicely: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI
northwest_nfts 5y ago
Yeah, that sounds similar to the idea of the Terrascope. I think the positioning of drones for the sun might be so wide to be infeasible for the next century. (Like, the drones would have to be in the Kuiper belt) I haven't watched this YT video recently, but I think he also touches on a Sol-scope and a Jupiter-scope https://www.youtube.com/watch?v=jgOTZe07eHA https://www.youtube.com/watch?v=jgOTZe07eHA
- deleted 5y ago
  [deleted]

pavlov 5y ago

Would Sol look obviously inhabited on the radio spectrum? This is a common sci-fi trope (“Contact”), but I have no idea whether it’s actually true that our radio emissions would be trivially detectable tens of light years away.

wyldfire 5y ago
What if they had an array similar to the one used in "Contact" to receive the response?
fermuch 5y ago
Our radio waves have traveled for about 200 light years. Proxima centauri, our closest star, is located at 4246 Light years from us. Very, very unlikely that someone can hear us, even if they tried. Space is huge.
- gpderetta 5y ago
  I think your Alpha Centauri distance is off by 3 orders of magnitude :) Edit: I think there are thousands of stars within 200ly of Earth.
  - _q8zh 5y ago
    Here's an interactive 33ly radius model: https://gruze.org/fly_10pc/ https://gruze.org/fly_10pc/ - left click + drag, mousewheel, right click. Could be more efficient, but this interactive does the trick; shows how loaded our neighborhood is. Going to hamburger menu -> settings -> show labels brings it to a crawl, though filtering objects helps that a bunch. Showing only stars with known planets is rather interesting.
    - BoxOfRain 5y ago
      This is really cool! Definitely going to be a time sink for me!
- ajakate 5y ago
  Proxima centauri is actually ~4 light years away. Space is really big, but there are a handful of stars in relative vicinity of us (under 250 ly) https://en.wikipedia.org/wiki/Proxima_Centauri https://en.wikipedia.org/wiki/Proxima_Centauri http://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Back/50lys.html http://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Ba...

f00zz 5y ago

Crazy to think that we have catalogued thousands of exoplanets, even though we basically can only detect them if they pass in front of their stars along our line of sight. Space is big, but also pretty crowded.

Aerroon 5y ago
I think it's more that we cab tease out a lot of information from very little data by just making some assumptions (physics). This is also why it's so difficult (impossible?) to anonymize personal data - very little of it can lead to understanding who you are. It is remarkable what astronomers/physicists have achieved though.
holoduke 5y ago
And probably there are more roque planets than planets with a star. Those are even harder to detect.

bulatb 5y ago

Event Horizon recently interviewed Lisa Kaltenegger (coauthor here) and Jackie Faherty about a similar paper they wrote: "Past, present and future stars that can see Earth as a transiting exoplanet." https://www.youtube.com/watch?v=W5CV6exdqcg&t=1m56s https://www.youtube.com/watch?v=W5CV6exdqcg&t=1m56s

dekhn 5y ago

People who are interested in learning more about transmitting information between solar systems should watch this wonderful talk: https://www.youtube.com/watch?v=sImBlq542TQ https://www.youtube.com/watch?v=sImBlq542TQ the author is a professor at harvard (known for writing 'The Art of Electronics' in addition to searching for extraterristrials) and put a lot of good thought into light transfer between solar systems. TL;DR a powerful enough laser that is well collimated would work.

Kattywumpus 5y ago

Aliens Can Watch ‘I Love Lucy’: https://www.lscheffer.com/tv.pdf https://www.lscheffer.com/tv.pdf

seventytwo 5y ago

What a fantastic question! I hope to see more of this kind of thing