[HN Gopher] Which stars can see Earth as a transiting exoplanet?
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Which stars can see Earth as a transiting exoplanet?
Author : colinprince
Score : 23 points
Date : 2021-10-27 21:27 UTC (1 hours ago)
(HTM) web link (academic.oup.com)
(TXT) w3m dump (academic.oup.com)
| pavlov wrote:
| 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 wrote:
| What if they had an array similar to the one used in "Contact"
| to receive the response?
| fermuch wrote:
| 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 wrote:
| 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.
| ajakate wrote:
| 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
|
| http://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Ba.
| ..
| ortusdux wrote:
| The inverse square law really dilutes out most signals -
| https://www.quora.com/How-far-do-radio-signals-travel-into-s...
| ThomasWinwood wrote:
| As I understand it the amount of time we were tossing radio
| into space was quite brief, and more modern radio traffic is
| directed at the ground (since after all if you're leaking
| signals into space you're wasting power).
|
| One of the papers cited in the OP argues that a good indicator
| that there's _something_ interesting about a planet is the
| combination of molecular oxygen and methane in its atmosphere -
| the former is a strong oxidiser, while the latter is a reducing
| gas, so there 's some dynamic system producing free methane in
| the atmosphere.
| f00zz wrote:
| 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.
| lmilcin wrote:
| 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 wrote:
| Yes. This video explains it rather nicely:
| https://www.youtube.com/watch?v=NQFqDKRAROI
| northwest_nfts wrote:
| 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
| [deleted]
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