# Can you find your way home from far FAR away? **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2008, 4:50pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570 "2008-12-10T16:50:02Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![shallora](https://avatars.discourse-cdn.com/v4/letter/s/f9ae1b/32.png) [@shallora](https://boards.straightdope.com/u/shallora)\ **Post date:** [December 10, 2008, 7:18pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/21 "2008-12-10T19:18:43Z")
> [@fiddlesticks](#): > > This is the responsibility of the stellar cartography division. Presumebly in the far future, your iSpacePhone will have a MilkyWayMap app so you can plot your way home. I can hear it now: _“Turn left in 20 parsecs . . .” “. . . 10 parsecs until your left turn . . .” “Turn left now. Earth will be the third rock away from the star ahead of you.”_ ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [December 10, 2008, 8:03pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/22 "2008-12-10T20:03:35Z")
If you’re sufficiently far away, how would you identify the Milky Way? ---
**Author:** ![ShibbOleth](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@ShibbOleth](https://boards.straightdope.com/u/ShibbOleth)\ **Post date:** [December 10, 2008, 8:09pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/23 "2008-12-10T20:09:23Z")
I’d probably just hitch a ride on a passing Vogon ship, maybe listen to some poetry and chill whilst they do the driving. So, somehow there is the technology to get across the 'Verse and back, yet not the spaceship equivalent of a Garmin? ---
**Author:** ![74westy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/74westy/32/3950_2.png) [@74westy](https://boards.straightdope.com/u/74westy)\ **Post date:** [December 10, 2008, 8:26pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/24 "2008-12-10T20:26:53Z")
> [@Sofis](#): > > If you have any time-keeping device, you can show them. If you don’t, you can demonstrate a unit of length (for example, I can define a metre by stating that I am 1.78 m tall), and then express the speed of light using that unit of length (it’s about 3\*10^8 m/s) and derive a unit of time from there. Would it be easier and more accurate to say, “the time it takes for light to travel 168539325.842696 times my length in a vacuum” or “the time it takes me to say ‘one thousand and one’”? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 10, 2008, 8:35pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/25 "2008-12-10T20:35:45Z")
As far as the T-shirts go, the local Society of Physics Students was selling one a couple of years back with the Pioneer plaque and the caption “Attack here”. ---
**Author:** ![davekhps](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@davekhps](https://boards.straightdope.com/u/davekhps)\ **Post date:** [December 10, 2008, 8:37pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/26 "2008-12-10T20:37:29Z")
Well, to find Earth, first you need to find the Arrow of Apollo, then you need to find the Eye of Jupiter, then you need the Final Five Cylons. . . (Sorry, Battlestar Galactica references. . . 🙂 ---
**Author:** ![Sofis](https://avatars.discourse-cdn.com/v4/letter/s/e5b9ba/32.png) [@Sofis](https://boards.straightdope.com/u/Sofis)\ **Post date:** [December 10, 2008, 11:43pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/27 "2008-12-10T23:43:08Z")
> [@74westy](#): > > Would it be easier and more accurate to say, “the time it takes for light to travel 168539325.842696 times my length in a vacuum” or “the time it takes me to say ‘one thousand and one’”? Well, that first one may be more accurate, and the second one is certainly easier. I was thinking mainly in terms of what I could achieve using only knowledge I already had lying around in my head, because I’m frankly not about to memorize anything to ten significant digits just in case I’m kidnapped by aliens :). ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [December 11, 2008, 1:14am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/28 "2008-12-11T01:14:08Z")
How about knowing how long ago supernovae were visible on Earth. There are three whose years I recall: 1054 producing the Crab Nebula 1572 Tycho’s supernova 1604 Kepler’s supernova I don’t know that those were the last three supernovae in our galaxy as there might have been some hidden to us on the other side of the core. But assuming the aliens could identify those supernova locations, it should be a fairly easy geometry problem to find the intersection point of the three spheres. If I know just the year the supernova were visible I know the radii of the spheres to one-light year. I think that would get me close enough to find home. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 11, 2008, 1:20am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/29 "2008-12-11T01:20:38Z")
> [@ZenBeam](#): > > [All you need is a T-shirt](http://www.thinkgeek.com/tshirts-apparel/unisex/sciencemath/6e90/?cpg=ab). I have that exact shirt. I’m not wearing it at the moment, though, so if I’m abducted by aliens, I’m pretty well boned. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [December 11, 2008, 1:22am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/30 "2008-12-11T01:22:34Z")
Of course, most of the abducted folk in question are male. So, we can’t ask for directions. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 11, 2008, 3:33am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/31 "2008-12-11T03:33:48Z")
> [@](#): > > How about knowing how long ago supernovae were visible on Earth. There are three whose years I recall: Ooh, good one, if you’ve got the help of friendly aliens. And don’t forget Supernova 1987a, which also has the advantage that you could point at the Magellanic Clouds to make it clear which one you mean (unless you happen to know the galactic coordinates of the other three). ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [December 11, 2008, 4:31am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/32 "2008-12-11T04:31:18Z")
> [@Chronos](#): > > Ooh, good one, if you’ve got the help of friendly aliens. And don’t forget Supernova 1987a, which also has the advantage that you could point at the Magellanic Clouds to make it clear which one you mean (unless you happen to know the galactic coordinates of the other three). True three spheres will intersect in two points so a fourth would help. Also there would be more intersections since each year could correspond to any of the three supernovae. Even though some of the intersections might be far outside the galaxy, I suspect pinpointing one would help a great deal. ---
**Author:** ![Geekboy](https://avatars.discourse-cdn.com/v4/letter/g/51bf81/32.png) [@Geekboy](https://boards.straightdope.com/u/Geekboy)\ **Post date:** [December 11, 2008, 4:42am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/33 "2008-12-11T04:42:18Z")
> [@Chronos](#): > > Ooh, good one, if you’ve got the help of friendly aliens. And don’t forget Supernova 1987a, which also has the advantage that you could point at the Magellanic Clouds to make it clear which one you mean (unless you happen to know the galactic coordinates of the other three). The problem there is local units again. How do you tell them how long a year is? And you probably need to know a pretty exact time as to when the nova became visible on earth. Even a teeny error here is going to be magnified to YF proportions. > [@ShibbOleth](#): > > So, somehow there is the technology to get across the 'Verse and back, yet not the spaceship equivalent of a Garmin? Of course there is a SpaceGarmin. But what do you tell them to punch into it as a destination? “Earth” or “Sol” isnt going to mean much to them when they know the star as “FLXPITTLE 6716252a” I think pulsars might end up being the only way to go. Which DOES mean jewlery of some sort, unless you want to go the “never ever take your smelly t-shirt off” route ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [December 11, 2008, 4:45am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/34 "2008-12-11T04:45:51Z")
> [@Rhythmdvl](#): > > What about getting a tat based on the [Golden Record](http://voyager.jpl.nasa.gov/spacecraft/goldenrec1.html)from the Voyager probes? > [@Geekboy](#): > > Or are we looking at a market for groovy medallions here? Obviously you should have the pattern woven into your towel. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 11, 2008, 4:51am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/35 "2008-12-11T04:51:30Z")
> [@](#): > > The problem there is local units again. How do you tell them how long a year is? By showing them a second, or a minute, or hour, on my wristwatch, and then telling them how many of those are in a day and how many days are in a year. Sure, that won’t be perfectly precise, but assuming that they can measure my watch to 1% or so (and they should be able to do better than that, especially if I use a relatively long time like an hour for calibration), that gets us down to a region about ten lightyears across. From there, I can use constellations, or just tell them that it’s the solitary G star in that region. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [December 11, 2008, 5:03am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/36 "2008-12-11T05:03:05Z")
> [@Geekboy](#): > > The problem there is local units again. How do you tell them how long a year is? And you probably need to know a pretty exact time as to when the nova became visible on earth. Even a teeny error here is going to be magnified to YF proportions. If I have a watch, no problem. If not I can probably count off a minute to 5% accuracy. I’m not at all worried about the exact time of the supernova. If I know the year I should have accuracy to a light year. If I get within 10 light years of the sun, there’s no problem at all. The sun is the only star of its type in that range except Alpha Centauri A and that’s part of a triple system. 50 or 100 LY would probably be fine. In particular the former would certainly be OK if they can pick up all the radio signals we’ve been putting out for more than that long now. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [December 11, 2008, 5:15am UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/37 "2008-12-11T05:15:31Z")
Sorry duplicate reply ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [December 11, 2008, 12:05pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/38 "2008-12-11T12:05:46Z")
> [@Sofis](#): > > Of course, that requires you to be able to communicate, but if you’re patient, the aliens can probably teach you their language. Unfortunately, to properly pronounce it they would need to rip out your tongue. ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [December 11, 2008, 12:37pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/39 "2008-12-11T12:37:40Z")
The trade language is basically a combination of farts and tap-dancing. The Boskonians developed it for amusement purposes. ---
**Author:** ![Sofis](https://avatars.discourse-cdn.com/v4/letter/s/e5b9ba/32.png) [@Sofis](https://boards.straightdope.com/u/Sofis)\ **Post date:** [December 11, 2008, 12:59pm UTC](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570/40 "2008-12-11T12:59:18Z")
> [@msmith537](#): > > Unfortunately, to properly pronounce it they would need to rip out your tongue. There is certainly a risk that the aliens’ languages use sounds the human speech apparatus can not produce (and that’s assuming they even use sound to communicate). However, if they communicate with other species on a regular basis, they probably have a variety of artificial languages designed for interspecies communication, and the odds of one of them being a decent fit is probably pretty good. And if humans are the first friendly sentient species they’ve encountered, they’d probably be willing to create a language to communicate with us. [Previous page](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570.md?page=1) [Next page](https://boards.straightdope.com/t/can-you-find-your-way-home-from-far-far-away/476570.md?page=3)