[wind noises]
Ok, I'm trying to find this line and I can see there's like a dip where the pass goes
around here and the line looks like it's just on the far side of a fence which is the top
of this hill here we go
okay it's basically on the other side of this gate
I think it might be on the other side of that field I think we'll come up the wrong side
I think it's that gate that gate over there yeah that is definitely it that's it they're
right there we got this
okay it's right before the diagonal path merges with a path we're on and I would say it's
here
yeah yes right right here there are three different definitions of North you've got
True North you've got magnetic north and you've got grid North and for the first time ever
all three of them have aligned in the UK at exactly the same place and that place is here
as of November in the year 2022 they did a line just out there in the ocean but the pointers
moved it's currently here it's going to keep going that way and it will pop out the other
side in Scotland around July 2026.
now there's the obvious question why is this point moving around but before we deal with
that I'm gonna find somewhere less windy probably dangerously on the cliff somewhere and we're
going to look at why we have three different Norths ah
okay True North as it says best North if you've got a spherical spinning object and I like
to carry a prop with me to demonstrate a sphere it is my head uh that North there it is right
there now the planet is on an angle and it spins but that Center of rotation is the top
of the planet it's it's the top it's the same distance from the equator in every direction
it is North there's no arguing with true north however
grid North is what you get on a map so this is an OS map the Ordnance survey have been
mapping the United Kingdom since the late 1700s and they sell these fantastic maps and
I love rambling it's a great hobby my wife and I go on walking holidays own a lot of
these maps and yes they have an app but that's just recreating the experience of having a
physical bit of paper a big rectangle big square of paper and you use a compass to navigate
around it and on this they like to put a grid the issue is True North makes for an awful
awful grid but to explain that like I'm going to live with you here it's been raining a
lot on the walk over the wind is freezing cold and if I know future Matt like I think
I know a future Matt on the way home future Matt's gonna go to a pub for a warm drink
probably a pub with a hilarious maths name so I'm gonna hand over the explanation for
what grid is used on a map to Future map
oh yeah I found a pub it's super warm and it's called the square Encompass so good if
you ever endorse it I highly recommend coming along they have an incredible range of both
beers and and crisps chips if you're Americans but anyway I brought this myself this is not
available in the pub this is my spherical chalkboard I think none of us should be surprised
I have one of these it's actually my wife's she uses it for drawing uh like she's a solar
physicist and so she's all solar configurations on this let me borrow it so I can demonstrate
that if you've got your equator kind of down here that's the equator line and then I draw
in this line of longitude so I'm going from the equator down here all the way up to the
true north that circle at the very top up there and then let's say I'm a map maker and
I'm like oh I definitely want to have this bit on my mat and I want to have the next
grid line over so I'm going to draw in the next line of longitude over oops over there
there we go and then of course they meet at the top if they start a part of the Equator
and they meet at the top they've got to get closer together as they go up so your map
maker comes along it's going to stay there excellent and they're going to make their
map on a flat flat surface and they start by putting in their central line so they're
like this is the beginning of my grid right down the center there there we go look at
that first line of the grid so far so good and actually we can line that up really nicely
so file out the bottom of this one with the bottom of that one and then I curl it up I
can perfectly match that line at the Top If I tip it right forward I can put that there
no problem and if you've got a flat surface you can absolutely curl it in that one dimension
no problem you're like well I need to do the other line now so actually the other line
it starts there so you know what I'll just very quickly put in the next line of migration
starts there I'm going to run it parallel as a map maker I really just kind of feel
it Go by eye I feel like that's that's pretty parallel so then you're like oh amazing right
so I pop those down there look at that line up with the two lines no worries this Center
one goes all the way up and look at this way off it's all the way I mean I'm covering a
decent percentage of the globe right so it's even past the line after the next one the
whatever the case we can agree this line should be over here should be there and it's ended
up over here and if I did do it there I'll add that in as a dotted line if I if I break
this uh it's going to be a real awkward conversation when I get home so there we are so that's
so if I actually followed True North this is what my grid would be doing it would be
narrowing in so that's not desirable so it turns out because of the nature of taking
a 2d surface mapping it on to a 3D sphere you can pick one line to line up perfectly
and the rest are going to be a bit off so when the OS Maps were working out their Maps
they're like well we could use Greenwich on the Zero line of longitude but instead we're
going to go with two degrees west and that's because it's kind of the closest whole line
of longitude so an integer value of longitude that's as Central as possible and because
the further out you go the worse the alignment of True North to grid North becomes you want
to minimize that distance and so two degrees longitude is like the minimal value of the
maximum error you're going to get in the UK and so that's why uh past mat is on the two
degree line of longitude right now even as we speak back to you past Matt yep still here
still cold been waiting the whole time and I am on that two degree line of longitude
however if I wanted to go to the three degree line it's just over 70 kilometers in that
direction and the one degree line is just over 70 kilometers in that direction however
by the time you get up uh north of Aberdeen uh up in Scotland where this line leaves the
UK at that point it's under 60 kilometers between the lines of longitude so if you use
True North to do your grid by the time you get up there you've got 84 a bit of 84 percent
as much land between each pair of lines you effectively Zoomed In by about 19 and that
changes gradually As you move up and the target mirror these people they like their scales
they're going to get real upset if the scale is changing the only good thing to be said
about grid North compared to True North is that once you compensate for that correction
like you know how far you are from two degrees you work out how far you've got to change
it stays the same if you're there at any point in the past or future it's always the same
correction it doesn't move around unlike
magnetic north is the worst but it's real easy to measure you just need a compass get
yourself a Shiny Rock with some other properties let it suspend and It'll point to North so
even though it's a bad North it's really easy to measure and the reasons it's bad is it
moves around which is why we're gonna get this freak alignment magnetic north is moving
which means it's going to line up with the other two however I said right at the beginning
that this Confluence of North by North North is moving up the line of two degrees longitude
you think well hang on if magnetic north has moved to line up with the other two it should
line up the whole weight I mean that's just the direction of north but that's not how
magnetic north works it's even worse than that it's not just that it moves around it's
not just that the self-magnetic pole can't even have the decency to be in Antarctica
they're shooting all over the place but the lines themselves aren't straight I mean this
whole planet is just a sloshy mess speaking of which Back to Future Matt in the pub magnetic
fields are a mess and a compass is not a smart device all it can do is orientate itself with
whatever the local fields are and if there's nothing else in the way that's great but if
I bring my phone over and here I've actually got my compass app running so I'm like oh
you know what I want to verify analog with digital if I bring the two together suddenly
the analog moves around because there are magnets in my phone it's changing the local
magnetic field now it's coming back and now it's going wrong again so the compass just
shows you whatever is happening in the local magnetic environment and the Earth is not
one perfectly neat magnet it's not like the lines come out of the top are perfectly straight
and go in the bottom oh no they go all over the shop the lines are going this is where
the lines are going that way I actually downloaded from uh the department Noah from the US government
this is a 3D 3D model of the Earth uh actually they give it as a flat model I've mapped it
onto a sphere because please flat models so I've taken their data put it onto this sphere
and I can drag it around and so the lines are showing you now they're showing you how
far off your compass is but they're not showing you how far off your compass is from where
the field should be pointing where magnetic north is because that's all over the place
if you look at the moment magnetic north at the top here is like over here somewhere oh
no there it is is it over there near Alaska I think if you look at the southern south
there it is it's over there like it's not even in Antarctica I don't know I bring it
up a lot really bugs me I feel like someone should look into that however uh the magnetic
poles move all over the place and this is not showing you where they should be it's
showing you the difference between the wonky local field which we call the declination
of the Earth's magnetic field and true north so it's just showing you how far off by accident
the magnetic field is compared to where you care about and you've either got the red lines
that's where it's pointing I think too much to the east you've got the blue areas where
it's pointing too much to the west and because of the intermediate value theorem you've got
the green zone that's where it's perfect doesn't mean it's pointing in the right direction
it just means that the magnetic field is messed up in a way that it accidentally compensates
for the difference between the magnetic north and the true north and if you look at these
lines there's one that goes from the South Pole through Western Australia up to the North
Pole there's another one that starts at the North Pole comes down then goes back up again
and look at that it goes right or zoomed in too much there it goes through the UK so this
data is from 2019 and you can see at that point it went pretty much through London so
if you're in London and you've got your compass out just because of the mess of the magnetic
field it would accidentally Point towards True North you didn't have to correct for
it and that green line that line of accidentally don't need to fix anything is moving to the
west and as you can see it's not a bit of a tilt and if you're moving a line it's on
a bit of a tilt so here I've got our original perfect line from my map and let's say this
ruler is the the zone of no correction if I gradually Slide the zone of no correction
across and you follow where it intersects with the only line where grid North equals
True North it looks like it's moving North up that line but that's just because the line
of zero correction is on an angle and it's moving from the East towards the west and
that's why that point is moving gradually up that line so there you are at this one
particular point in time there's one specific spot I can look at my map and grid North is
that way True North is that way magnetic north is that where they all line up well if I hold
everything still they all line up perfectly in that I think my compass there it goes it's
rotating very slowly to point in the correct direction I'm so excited and it's going to
move across the UK going through such hot spots as Birmingham probably other places
as well we'll put them on the screen system
the m62 motorway Barrack upon Tweed Aberdeen Fraser Bird go and check him out eventually
it goes out The Far Side just north of Aberdeen place called fraserburgh we think roughly
July 2026 if you're planning ahead for that party um but the Earth is a sloshy mess so
who knows but what an incredible alignment I'm so glad I'm here absolutely worth being
this freezing cold and Windswept if you excuse me I have a future mat to go and become thank
you so much for watching this video where I've tracked all the way to the edge of a
cliff to talk about three Norths all at the same point and don't forget to like And subscribe
hey look I didn't come all the way here in the wind and rain for future Matt to do the
wrap up in the pub I'm in the past I've earned this I am the pain before that gain I know
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