Geohashing

Posted byRandall 246 Comments on Geohashing

Almost four years ago, I posted a comic laying out the Geohashing algorithm. The algorithm generated a set of random latitudes and longitudes each day, spread out across the globe so there was generally always one within a few dozen miles of every location. I figured they could be used for hiking destinations, sightseeing, meetups, or whatever else people came up with.

I wanted to make an algorithm that anyone could implement, which didn’t rely on a central authority or ongoing support from any one maintainer. I also wanted to make it impossible to know the locations more than a day or so in advance, so that if geohashing became popular in an area, no one could publish a list of future locations that woud give property owners, park rangers, or local police time to prepare. So each day’s coordinates are randomized using the most recent Dow Jones opening price, which isn’t known until the morning of that day—or, in the case of weekends, a day or two in advance, which helps with planning larger weekend trips.

In the days after I posted the comic, there was a flurry of geohashing activity, which quieted down as the initial novelty wore off. But it didn’t die, and for the past several years there’s been a small but vibrant community building around the Geohashing Wiki. There are numerous daily expeditions, and they’ve taken some beautiful pictures and come up with a lot of neat tools, games, and achievements.

One of the many things they did was use a tweaked version of the algorithm to come up with a globalhash, a single coordinate for the day somewhere on the planet (biased toward the areas near the poles). They’re usually over the ocean, but a few of the land ones have been reached.

Yesterday’s globalhash fell less than a kilometer from the South Pole. User Carl-Johan got in touch with the Scott-Amundsen research station, and later that day, the hash was reached by Katie Hess, Dale Mole, and Joselyn Fenstermacher of the US, Robert Schwarz of Germany, and Sven Lidström of Sweden.

Wow. Just wow. Congratulations.

If you want to look up today’s geohash for your location, you can use this online tool, or one of the others listed on the Coordinate Calculators page.

246 replies on “Geohashing”

  2. I love scientists. Their willingness to go out and do something cool (literally and figuratively, in this case) is always inspiring. Way to go, all of you!

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  4. And so, upon receiving the Geohash, the scientists thought: “So, it has come to this.”

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  6. This is not relevant to this post – however, I found no other place to hopefully get this message across.
    As it happens – my uncle Bob (from my mom’s side) is the President of the IAU (http://www.iau.org/administration/membership/individual/3626/) – and so I had a special laugh at your comic (http://xkcd.com/1020/) about Orion. Hopefully I can find a way to forward this along to him as I’m certain he would get a good laugh.

    Thanks for always entertaining XKCD.

    -Andrew Colclough

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  11. When travel between planets in our solar system is possible, will we need a solarhashing algorithm, for finding points in space in our solar system?

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  12. @Ash Walker
    Then you just add a third coordinate for height from the Earth’s surface (ex 42.848514, 78.133092, 14000000)

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  13. @Trent assuming it could be measured well enough, distance from the center of Sol would drive us a little less nuts.

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  14. Ok. Someone needs to make a five million pixel tall ribbon for these guys. *This is a moment in xkcdhashing history*

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  15. Get geode.

    Cut into smallish pieces.

    Combine with potato, onion, and oil in a pan.

    Cook until done.

    Don’t eat.

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  18. @Awkward Engineer: I used to work down at Amundsen-Scott–the US gov’t actually does give you a little “Antarctic Service Medal of the United States.” Sure beats all those “Participant” ribbons from childhood. And adulthood.

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  20. @Bill: See the talk page at the page called “globalhash” on the geohashing wiki… the idea was apparently a nonstarter

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  22. A geohasher here.

    This is a really ‘cool’ expedition! 😀

    Having said that, I hope some of the people reading this will realize how fun Geohashing really is and will jump in. It’s always fun to get new people, and it also increases the probability of a hash meet-up.

    Just check out the http://geohashing.org for more expedition reports and photos or come hang out at irc.foonetic.net #geohashing.

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  23. > I love scientists. Their willingness to go out and do something cool (literally and figuratively, in this case) is always inspiring. Way to go, all of you!

    Not just cool, but pointlessly fun too.

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  24. @Trent
    That would still constitue a circle, given that the coordinates are valid whole 24 hours 😀

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  25. Wow! My day has just become amazingly surreal! I get an email from Amazon saying they noticed I had looked at memory cards on their website. Which leads me to some reseller of memory cards with some weird dribble about xkcd in the advert… thoroughly intrigued yet somewhat confused, I click on the link and discover xkcd for the first time… What do I see first? “So… It has come to this.” I spend the next hour clicking through random strips, laughing my head off, feeling like I found a new home, when I see the link at the top of the page referencing Geohashing…so I drop in…

    Finding the characters in here are almost as funny as the characters in the strip… I can rest assured that the future will be okay no matter who wins the election or whatever becomes of magnetic pole shifts… With folks like you all around… I know I can find a smile. Welcome Home.

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  27. (Composed at 4:15 February 27th, posted 8:54 February 28th)
    @Trent
    http://maps.google.com/maps?q=42.848514,+78.133092
    14 million units above a road (near the town Kuturga, apparently) crossing a river feeding into the large lake Issyk Kul in Kyrgyzstan. If those units are feet, then Google suggests 4267.2 kilometers, which it also tells you is the number of miles between Tunisia to the Dominican republic (how it defines this I do not know). Anyway, that is about 2,651 miles; to put that in perspective,
    http://www.centennialofflight.gov/essay/Dictionary/ORBIT/DI153.htm
    says low-earth orbit is about a hundred miles up, and that geosynchronous is 22,300 miles up.
    I think your ‘height from Earth’ thing would favour hashes near Earth just as globalhashes favour poles, as the normal lines (of height) diverge the farther from Earth one gets. Also, having Earth as the center would be pretty meaningless for the other planets.

    @Ash Walker
    I suspect, distances of space being what they are, most people would hash around planetary (or other) surfaces anyway, so it would be geohash coordinates + a height like Trent said, plus a specification of which ‘geo’ one is hashing (Ceres, for instance). To determine which planet’s (or other body’s) airspace (spacespace?) one is in, one could use Voronoi regions.

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  30. The guys and gals down at Amundsen-Scott are awesome. I heard them on ham radio Christmas eve and couldn’t quite get in, but through a confusing series of professional connections, got a sat-phone call from one of the researchers down there to get a scheduled contact set up.

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  32. i was terriblly confused as i thought gulash was one of my mothers hungarian recipes, which i will gladly share with anyone who wants to share in my mothers hungarian gulash recipe

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  34. AwkEng (Sam), they already have the merit badge “We work at the South Pole, bitches!” which is second in impressiveness only to “We work in OUTER FRAKKING SPACE, bitches!”

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  39. Really glad to see this thing has taken off and all, and real props to the Research station crew.

    But… Whilst I guess I can see the rationale behind it… People ought to know better than trek to a geohash where property owners, park rangers and local police might have an issue with you being there in the first place.

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  40. Pingback: XKCD Web Comic #1023: Late-Night PBS (described for blind and visually impaired) — BlindGadget

  41. This is such a great idea, I plan to get a new bike soon, and I hope to trek to weekend geohash spots!

    I wish the 20Km Fukushima Nuclear reactor evacuation zone wasn’t in my area, though…

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  43. Unfortunately, the algorithm doesn’t work so well for Istanbul since every meet-up almost invariably ends up being over the water.

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  44. Meanwhile in religion someone reads some dumb 2000-year-old story, hates gays, and believes the earth was made in 7 days.

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  45. Do these brilliant people and their epic achievement qualify for the ‘Walking on water’ geohash? The qualifying criteria rules out snowpack and glaciers but not continental icesheets! Just being a geographer…

    If not, at least they’ll get a South Geohash achievement.

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  46. What a cool story. I wish *I* worked at the South Pole. I also wish I had money so I could drop in on a geohashing site… Maybe one will pop up in my area soon.

    @John Meyers: Your comment was both rude and ignorant, and it contributed nothing of value to the discussion. You’re entitled to your opinion of religion, but please refrain from using any flimsy excuse you can find to bash religious people.

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  47. It would appear that for the moment, the wiki’s servers are down.

    Also, I’m pretty sure ChloeSunglasses is a spambot (generic response, link to a shopping website, etc)

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  50. Could do the math with a ten mile tail wind a d a push, but for us poorer, less mobile folk who still have not either calculated a higher being nor disproved its presence (in whatever number of days you think it takes to create something), it may be more inclusive to tweak the algorithm so that the available points of interest for a day ( or weekend) re equally distributed across public areas on surfaces that have handicapped access, no walking in water. Or having to move mountains or perform other fantastic feats that may be confused with supernatural abilities by lesser beings, or those of us who cannot afford a parka. Now where did that squirrel hide my spark-gap transmitter and Morse code kit? I am going to need to start using my toes to count XKCD episodes!

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