Timeline for How to describe the Sun's location to an alien from our Galaxy?
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
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| Oct 1, 2023 at 3:53 | comment | added | Dawood ibn Kareem | Oh this is frightening! How can we know whether the aliens who read the Pioneer data would be hostile? It seems to me that broadcasting our exact location would be rather like deer painting themselves in luminous colours during hunting season. Did someone at NASA make this decision on behalf of everyone on Earth? | |
| Sep 29, 2023 at 13:36 | comment | added | Vaelus | NASA could have avoided describing an arcane distance unit for triangulation by using barycentric coordinates, which are unitless. | |
| Sep 28, 2023 at 21:05 | comment | added | gomennathan | To see a pulsar, you have to be on the surface of a cone painted by its beam. If you take the ones visible from Earth, to see them somewhere else many of these cones must all intersect. It seems unlikely unless the pulsars are very far away (outside the galaxy). | |
| Sep 28, 2023 at 17:35 | comment | added | Steve Jessop | @J.A.: "I also wonder how many people would be able to recollect these numbers " if they're interested in pulsars they might very well remember the location and characteristics of whichever ones they work on. Knowing their earth-based astronomical co-ordinates is good enough, because to triangulate you need their angles relative to each other as viewed from earth, and as viewed by the aliens. Not necessarily the same pulsars as on Pioneer, unless they're also interested in the Pioneer plaques. As ProfRob says, though, whether that actually helps is a separate issue. | |
| Sep 28, 2023 at 14:48 | comment | added | ProfRob | @Hobbamok I agree you might be able to pick out the Sun from $\sim 100$ similar stars. There are about 100 sun-like (0.9-1.1 solar mass - note that mass is not directly observable) within about 50 light years of the Sun. The main point is that you won't be able to see those pulsars from another position in the galaxy so you will have no accuracy whatsoever. It is not just me that says so - read the cited link to forbes.com. | |
| Sep 28, 2023 at 14:25 | comment | added | Hobbamok | I mean it doesn't need to be SUPER accurate, just accurate enough for our sun to be the only "sun-like" star in the potential target area. Or one of a couple because with sufficient telescope capability you could find the sun within a set of a couple hundred similar stars | |
| Sep 28, 2023 at 11:39 | comment | added | ProfRob | To amplify; despite what it says on the wiki page about that plaque; pulsars typically "pulse" for a few million years before switching off, may be unidentifiable from their periods long before this and often have velocities so high that they will have moved hundreds of light years in a million years. If we can assume no significant time-lag and we are still reasonably close to the Sun it could work, but the pulsed radiation is typically confined to a cone with an opening angle of a few degrees. This means that in any random Galatic position, the chance of seeing a pulsar is very small. | |
| Sep 28, 2023 at 7:19 | comment | added | ProfRob | This doesn't work. Pulsars are ephemeral and their light is beamed. The same set of pulsars cannot be seen elsewhere or elsewhen in the Galaxy. | |
| Sep 28, 2023 at 7:13 | comment | added | ProfRob | astronomy.stackexchange.com/a/39514/2531 | |
| Sep 28, 2023 at 5:42 | comment | added | J. A. | I also wonder how many people would be able to recollect these numbers (i.e triangulation of Earth's location by using pulsars) if they are suddenly caught in circumstances as described in my post - perhaps even if they are professional astronomers? | |
| Sep 28, 2023 at 5:40 | comment | added | J. A. | Thank you! I'm not sure though it is something that can translate to a few numbers that someone can easily/realistically memorize and carry in their head. I take it that the numbers must be memorized with very good precision + location of those pulsars should also be captured somewhere? Also, I guess another thing would be to better memorize numbers using Planck units or knowing how to translate to/from (or as you suggested "hyperfine transition of hydrogen")? | |
| Sep 28, 2023 at 5:36 | history | edited | planetmaker | CC BY-SA 4.0 |
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| Sep 28, 2023 at 5:30 | history | answered | planetmaker | CC BY-SA 4.0 |