2,774 miles traveled by a lone wolf

From the Voyageurs Wolf Project, a map shows the travels of a lone wolf over an 11-month period. Check out the animated version for full effect.

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Posted by in GPS, maps, nature, wolf

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Jewelry based on your GPS traces

GPX Jewelry by Rachel Binx lets you turn your GPS traces into jewelry. Just upload a GPX file from, say, your fitness app or Apple Watch, choose your finish, and you’ve got yourself a personalized pendant. Nice.

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Blockchain mapping

Shannon Mattern for The Atlantic on how blockchain might be useful in mapping and as a replacement for GPS:

Crypto-cartographers hope to use it for spatial verification—confirming that things are where they say they are, when they claim to be there. How might this be useful? Well, you could know precisely when an Amazon delivery drone drops a package on your doorstep, at which point the charge would post to your account. No more unscrupulous delivery drivers, and no more contested charges for packages lost in transit. Or when opening a new bank account, you could virtually confirm your permanent address by physically being there during a particular verification period, rather than providing copies of your utility bills. You could also submit a photo of your flooded basement or smashed windshield to your insurance company, supplementing your claim with time- and location-verified documentation. Or, as you pass by your local family-owned coffee shop, the owner could “airdrop” some Bitcoin coupons to your phone, and you could stop by to cash in before the offer expires a half hour later.

Oh good.

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Bill Paxton tribute through storm spotters’ GPS coordinates

Bill Paxton, who played a storm chaser in Twister, died on Sunday. To honor him, storm spotters gathered at various coordinates to form Paxton’s initials.

I don’t know much about storm chasing or the man, but this seems special. It’s like a hello sent to the skies.

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Flyover Country app tells you about the ground beneath as you fly

Flyover Country

Before your next flight, road trip, or hike, download the Flyover Country app available for Android and iPhone. The app tells you information about where you are at any given moment, or if you’re flying, the ground beneath.

The app exposes interactive geologic maps from Macrostrat.org, fossil localities from Neotomadb.org and Paleobiodb.org, core sample localities from LacCore.org, Wikipedia articles, offline base maps, and the user’s current GPS determined location, altitude, speed, and heading. The app analyzes a given flight path and caches relevant map data and points of interest (POI), and displays these data during the flight, without in flight wifi.

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Posted by in app, flying, GPS, maps

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The zero meridian, or something like it

CIMG1443This weekend I took my parents to visit the Greenwich Meridian – or did I?

The marked meridian on the site of Greenwich Observatory, where tourists line up to pose for silly pictures with one foot in the East and one foot in the West, has claimed to be zero degrees longtidude since 1884, but if you check your smart phone GPS on that spot, you’re NOT at exactly 0.000 degrees.

According to GPS, the zero meridian appears to be in a park adjacent to the observatory, and not in the section behind the fence that charges admission so you can “visit the meridian”.

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What’s going on here?

Earlier this month, an article by Stephen Malys and others in the Journal of Geodesy revealed the reason behind the discrepancy. The technology used in the 19th century to determine the location of the zero meridian was subject to local distortions from the Earth’s gravity and shape of the local terrain. GPS technology uses measurements from satellites, which aren’t affected in the same way as technology located on Earth.

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The dotted line is the much photographed meridian established in 1884. The solid line is where the GPS says it should be.

So the meridian really is in the wrong place. What does that mean for maps or for time? Well, the Ordnance Maps used in the UK were already using a slightly different zero meridian as reference point, because they were established before the 1884 meridian convention. And the effect of the new meridian location on Greenwich Mean Time, which determines Universal Time, is unnoticably small, so nothing much has changed.

Except, for a shorter line and a cheaper visit, you could technically skip the museum and the crowd of tourists and find the true GPS meridian about a hundred meters to the East of the Observatory in Greenwich Park. It’s probably not as fun a place for a family visit, though.

Aerial photo is Figure 1 from the article by Malys et al. (CC-BY). Photos taken from the ground are by me and by the man who was behind us in line at the almost-but-not-quite meridian line. I previously wrote about the history of the Greenwich Observatory on this site.


Filed under: Curiosities of Nature, Have Science Will Travel Tagged: GPS, gravity, greenwich, greenwich mean time, Greenwich Observatory, Greenwich Park, Journal of Geodesy, meridian, Stephen Malys