How We Solved the Greatest Riddle In Navigation

SUBSCRIBE so you don’t miss a video! ►► bit.ly/iotbs_sub
We’re on PATREON! Join the community / itsokaytobesmart
↓↓↓ More info and sources below ↓↓↓
Humanity’s drive to explore our planet is one of the defining characteristics of our species. But exploration only works if you know where you are at any given time. Not so easy when you are out at sea with no visible landmarks and the stars above you are in constant motion. It turns out that the key to solving this puzzle is understanding that in order to know WHERE you are, you have to first know WHEN you are.
References: sites.google.c...
-----------
High fives to all our Brain Trust Patrons:
NullBlox.ZachryWilsn
paul andre bouis
Mark Littlehale
Ali Freiburger
Mehdi Damou
Barbora Bei
Burt Humburg
Roy Lasris
dani bowman
David Johnston
Salih Arslan
Baerbel Winkler
Robert Young
Eric Meer
Dustin
Karen Haskell
Join us on Patreon!
/ itsokaytobesmart
Twitter
/ drjoehanson
/ okaytobesmart
Instagram
/ drjoehanson
/ okaytobesmart
Merch
store.dftba.co...
Facebook
/ itsokaytobesmartpbs

[@besmart]

Why is it so hard to keep track of latitude and longitude? Because they're all over the map! Two things: Not sorry for that joke, and I want to make sure you know that we have a Patreon where you can see new videos before anyone else and help support the show with no algorithms in the way: www.patreon.com/itsokaytobesmart

[@deleted-something]

Crazy

[@Durandel]

I feel like you need a link to the Map Men episode on Solving the Longitude as a foot note to this video.

[@manubhatt3]

Why did you change the name of your channel?! I liked the earlier one. Bdw, it's NOT Grenich but Greenwich(pronounced as Green Witch)!

[@FilosophicalPharmer]

Latitude and Longitude puns must be carefully coordinated. 👍🏼

[@FilosophicalPharmer]

@@manubhatt3 He’s using the American pronunciation. We’re “Two lands separated by one language.”

[@SlavaPunta]

The "purple star" example was far more interesting in reality. Dutch astronomer Christaan Huygens tested using the moons of Jupiter as a universal clock. Specifically using Io passing in front of Jupiter as a "time stamp." As he built the time tables for this, he was shocked to find the times drifted by some 20 minutes throughout the year. It didn't repeat "on time," despite having the correct period the next night. He correctly correlated the observed time shift to the changing distance between the earth and Jupiter as they rotate around the sun. Noting, it took longer to see the event the further away we were from each other. The light was late because it simply had further to go. Thus, giving him the first solid (and shockingly good) estimate for the true speed of light. Something that was purely speculative up to that point, but nobody had any evidence for.

[@ryancraigt]

I never knew that was how he measured the speed of light. That is very interesting and must of been bewildering for him to work through.

[@Hawk7886]

That's super damn neat

[@sindikit]

How does one check their "local clock" out at sea? Am I to assume they reset their watch every day at noon? But, if that's the case they would have moved since noon and then no longer be the same time. Maybe I'm missing something.

[@SlavaPunta]

@@sindikit The short answer is they used sundials. And I imagine sunrise, noon, and sunset would be an easy way to recalibrate for the day (but I honestly don't know what they did in practice). But you are correct. Time and location are fundamentally linked out at sea. Which is why it was so important to establish another reference point (Greenwich / Naval Time) to differentiate the two. That is the problem statement that drove the arms race for a seaworthy clock.

[@ironcito1101]

Wouldn't the period change according to the radial velocity, not the distance? If something happens every 1 hour, we'll see it happen every 1 hour, whether it's next door or a light-year away. Its period will only appear to get shorter or longer if the event is moving towards or away from us. Essentially like a Doppler effect, or blue/red-shifting.

[@anujarora0]

11:20 whenever Harrison asked for the prize, the committee attributed his success to luck and refused to give the prize. King George then advised Harrison to petition Parliament for the full prize after threatening to appear in person to dress them down. Finally in 1773, when he was 80 years old, Harrison received a monetary award in the amount of £8,750 from Parliament for his achievements, but he never received the official award (which was never awarded to anyone). He was to survive for just three more years.

[@takers786]

Why am i not surprised, terrible.

[@tylerdurdin8069]

See I told you he got cheated. You are going to receive a lot of flack for not mentioning this in your video.

[@idraote]

that's sad but not unexpected

[@EcceJack]

Yeah.... I think two other prizes were also awarded by the Board of Longitude, but it was also basically like pulling teeth to get them, and the total amount paid out was RATHER less than £20,000. One of the main reasons for that reluctance to part with the prize money is likely that the national purse had grown a bit tighter right around that time due to... oh, I can't remember exactly, some wars or other, probably.

[@andrewhoward6703]

Not only was he screwed up with a prize, but after so many years, it wasn't even mentioned on KZbin. I can imagine how he would feel now

[@jpetemadre2724]

There is a very enjoyable book with the expanded version of this story. It's called "The Illustrated Longitude" by Dava Sobel published in 1995. She first wrote "Longitude" without illustrations 2 years earlier, and her scientific community urged her to illustrate it. She did a masterful job. The clock shown in the video is actually the 3rd or 4th clock produced by Harrison, as he improved them and made them smaller. The first clock was much bigger. The trick was that the pendulum could withstand the rocking of the ship. And as stated, they denied Harrison the prize because he was a mere "tinkerer" compared to the scholars also working on the problem. He received the award at the end of his life.

[@jpsned]

I have another book by Sobel: "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time." It was published in 1996. Perhaps it's an update of the one published in 1995?

[@jpetemadre2724]

@@jpsned I re-read the publication page. The text copyright is 1995. The Introduction copyright, along with the copyright of The Illustrated Longitude is 1998. This goes along with the story as I remember it from around 1998. Dava Sobel first wrote the book as you describe it with that full title and no illustrations. It was very well received in the scientific community, and she was encouraged to produce it with illustrations, which she did. The reason the text copyright is earlier must be because she used the same text from the original book. I first learned of her and the book on a C-Span Book Notes program -- the original one hosted by Brian Lamb. She was the interviewee. She was an elegant lady, as they say, "of a certain age." Within the interview, she described how she learned that her book had made the bestseller list. She had a hobby of ballroom dancing and was enrolled one night in a Fox Trot competition. Right before her performance, a friend brought in a newspaper clipping with the news that her book was on the best seller list. The Fox Trot is a complicated dance, and one she often was nervous about. But after seeing the news of her book, she stepped out onto the dance floor with the thought, "I don't need to worry about this I am an author!" She and her partner won that night's competition. If you liked the first book, I highly recommend this one.

[@jpsned]

@@jpetemadre2724 I just found my copy and indeed it has no illustrations. (Very cool cover, though, with two circles cut out to show Harrison and his watch on the inside first page!) That's a very nice story about Dava Sobel and the Foxtrot. I took ballroom dancing lessons for a while and the Foxtrot was one of my favorite steps! Eventually I moved on to East Coast Swing and Lindy Hop. I also performed this type of music (I play woodwinds) all through high school, college and beyond, so it was exciting to learn the steps that went along with the music. One thing that was eye opening to me: the music was definitely written to be danced to, as opposed to just listening. The composers and arrangers clearly knew this as dancing to it was effortless--once you knew the steps. 🙂

[@jpetemadre2724]

@@jpsned Very interesting commentary about the music and dance. I've enjoyed this exchange regarding the book, also.

[@jpsned]

@@jpetemadre2724 Myself as well!

[@TSZatoichi]

I'm going to disagree with your disclaimer about the globe at 1:22. It has a unified Germany which happened on October 3, 1990, AND a still unified USSR which didn't dissolve until December 26, 1991. It looks like this globe was made between those times when the world of cartography got swept up in a frenzy of map making during the collapse of the Eastern Bloc never thinking that the work of redrawing the lines with the dissolution of the Soviet Union and the break up of Yugoslavia would happen so soon afterwards.

[@airbornefilip9139]

OOO, nicely done.

[@besmart]

This is my kind of detailed thinking!

[@micahbirdlover8152]

@@besmart I love this video 🥰

[@micahbirdlover8152]

@@besmart fancy 🍵 cup of tea very funny 🤭😃

[@micahbirdlover8152]

@@besmart great video 👍

[@Piffsnow]

I watch science videos on youtube for almost 10 years and I'm amazed to still learn so much from a video from time to time. Thanks for spreading knowledge!

[@Piffsnow]

@OfficialBeSmart What is the prize ?

[@SteveMcMief]

Great video! 10 years ago I went to theGreenwich observatory. Back then, there was this old man who gave this free tour. He explained the longtitude problem to us, the audience. Why they went from observing at the moon to building clocks. And oh boy, there are many old clocks on display at the observatory.

[@adorablegodzilla5628]

I've been there three times and never heard any of this, but saw some cool boat stuff.

[@stevenemert837]

@SteveMcMief - And four of those old clocks at the Royal Observatory are the actual, original H1 through H4 timepieces built by Harrison! H4, his 4th attempt, is the timepiece depicted in this video.

[@apkk5594]

@@stevenemert837 Also worth mentioning that H1, H2 and H3 will normally be running all the time. H4 is only run on occasion. BBC Horizon did an episode many years ago on Harrison. Since then Dava Sobel has published a great book on the subject. There was also two part Channel 4 drama staring Michael Gambon and Jeremy Irons which is excellent and tells parallel stories of the clocks development alongside their repair and refurbishment. One of the reasons that Harrison did not win the full prize was nothing to do with his skill or the clocks and watches he produced, it was because people expected the prize to be finally won by the almanac camp - aka astronomers. Basically, the competition was biased against him from the start.

[@Anonymous-df8it]

@@apkk5594 Why was it only run on occasion?

[@apkk5594]

@@Anonymous-df8it unlike the clocks, H4 is not self lubricating. The consequence is that the oil needed to run it will slowly degrade the watch and so they minimise it's use.

[@toastrecon]

Another fun fact about time and location: GPS algorithms have to take into account that the satellites' orbital velocity and the resultant distorted time. Anything moving experiences "time dilation" and if GPS devices didn't take into fact that warping of time, they wouldn't be nearly as accurate as they are.

[@Gerard1971]

Not completely true. The special relativistic effect due to the orbital speed which makes the clock appear 7 microsecond a day slower than on earth, is much smaller than the general relativistic effect due to weaker gravity which makes the clock in orbit appear 45 microsecond a day faster than on earth. The net result is that the clocks in the GPS satellites appear to run 38 microseconds a day faster than the clocks in a GPS receiver on earth. However, this time dilation is NOT included in the GPS algorithms, because it has already been corrected pre-launch by setting the clock speed slightly lower (10.22999999543 MHz) so it will produce the expected 10.23 MHz when in orbit. The only thing that the receiver has to do is compensate for the eccentricity of the orbits of the satellites and its own movement (which includes the rotation of the earth).

[@toastrecon]

@@Gerard1971 Interesting! Thanks for the additional info.

[@BenjaminCronce]

@@Gerard1971 I read that GPS satellites compensate for the gravitational field differences over different parts of the earth as they move around. Not sure how true this is. If only for ones of certain accuracy and precision or what, or maybe a fixed offset based on average orbital path instead of "real-time".

[@EduardoEscarez]

@@BenjaminCronce There is the ground segment of several stations that tracks each GPS satellite to verify its health, time and orbital parameters, then they update the satellites with the corrected time, ephemeris (the orbital parameters of each satellite) and the almanac (the state of all the network). Then the receivers downloads the time, ephemeris and almanac to get their own precise location. Also, to speed up things there is A-GPS (Assisted GPS), in which the smartphone can get the ephemeris and/or the almanac from the cellular network or the internet. That's why is faster to find your location when you have cell service than when you don't have coverage for a long time, because the GPS receiver needs more time to get all the data and then estimate its position.

[@toastrecon]

@@EduardoEscarez That's fascinating. GPS might be one of the most complicated and underappreciated technologies we routinely use.

[@MariaMartinez-researcher]

There's an excellent miniseries called Longitude which dramatizes Harrison's years of tinkering with clocks and how they were proven practical, and the obsession of a 20th century man for restoring Harrison's original clock models and make them function again.

[@terencemorales7894]

Great episode! It's always so humbling to realize just how brilliant some of our ancestors were and how much we take their efforts for granted. Also, anyone else constantly distracted by this man's flawless head of hair??

[@Krilonell]

I was not... you made me lol

[@DomCOuano]

i really love how knowledge compounds over time. nowadays, we have incredibly sophisticated technology that make navigation very easy. because our ancestors took the time to write down their findings when they went out exploring and getting lost everywhere. i wanna go back in time and say thanks

[@davidrust3169]

I inherited one of my professor's indignation at every person who attributed the Great Pyramids to aliens since that's so dismissive and disrespectful to those ancient engineers. They created something amazing! How dare we dismiss their accomplishments by attributing it to something for which there is no evidence and is, basically, "magic"! I applaud you, Smart Channel! :)

[@TokuNorth]

No evidence for aliens?? But, look in a mirror You are an alien, you live on a planet in space, and so would some other beings on a faraway planet in a faraway galaxy So yeah, there is evidence for aliens, you are one.

[@ws6778]

That is because of race-i.s.t anthropologists.

[@KebaRPG]

@@ws6778 Wait what if Ancient Aliens... Them Sudanese Green Card Workers stealing jobs from Real Hard Working Egyptian Citizens. /s [For those that do not get the joke Sudan has more pyramids - just smaller and different slope angles]

[@diablo.the.cheater]

@@ws6778 Those furrys of the poles really like to drive against each other in tracks at high speeds huh?

[@stephenmorton8017]

good point! aliens have taken over the miracle business.

[@taitano12]

Thanks for the walk down memory lane. I remember my grandfather teaching me this as a kid. He was a Naval History Professor, expert Navigator and Compass Adjuster.

[@cosmicHalArizona]

How fortunate you are to have those knowlegeable ancesters.

[@thepilotman5378]

I never thought about the ship's movement causing issues with the clocks. That's actually so cool to think about

[@dianapennepacker6854]

Yeah everything from movement, humidity, air pressure, tempature, etc etc can effect all of it. Hell even what your clock is made of matters. Seriously mechanical clocks are just amazing to me. Wish I grew up around watch makers. Ever see how many movements in some are, and how tiny the effin things are?

[@alancranford3398]

At the end of the 1990's I toured the Old Royal Observatory and looked at the H-1, H-2, and H-3 chronometers, stood on the Prime Meridian, learned the purpose of the red ball dropping daily. I did my research prior to an international field trip and got to enjoy myself.

[@NZ-fo8tp]

I am a Guidance, Navigation, and Control Engineer for spacecraft, and I approve this message. It really quite remarkable, my designs today still use a clock and a star map to figuere out where its pointing. Things have changed but not in the ways you might think

[@1yoav1]

A star map is the most accurate way but there are other ways like magnetic field or sun/earth sensors. I'm a satellite engineer

[@its2point072]

I started watching your videos when I was about 10 and they helped get me interested in history, science, and all that other nerdy stuff. Almost 6 years later and I still love all the videos. The team behind this channel are responsible for some of the best memories of my youth. Thanks guys ❤️

[@georgekappland2935]

I teach young aviators to do this daily. Most do not realize that this is where it all began. Great video!

[@neuralnetwork17]

When I was about sixteen this question really stumped me. I asked my geography teacher, and he said "you need a clock." It suddenly clicked, and it blew my mind.

[@Anonymous-df8it]

Yes, but if you go to 7 degrees longitude, the time will be the same as the time in Greenwich, so you still don't know where you are!

[@neuralnetwork17]

@@Anonymous-df8it No. At 7 degrees longitude your sundial will give you a time that is almost half an hour earlier than your clock set to Greenwich time. You can use that difference to calculate where you are.

[@Anonymous-df8it]

@@neuralnetwork17 Aren't sundials wrong due to the equation of time though?

[@neuralnetwork17]

@@Anonymous-df8it I wouldn't call the sundial wrong. I am of the (minority) opinion that apparent solar time is the "real" time. 😆 But you're right, the length of the day does vary, and if you don't account for that you have a margin of error of about three degrees. Luckily, people have known about this for millennia, and accurate tables for accounting for this have been available since the 17th century. And even if you don't have those it is extremely useful to be able to determine your approximate longitude to a few degrees rather than not at all.

[@Anonymous-df8it]

@@neuralnetwork17 Why do you need tables? Couldn't they come up with a formula that approximates the equation of time?

[@Raz.C]

I need to say this: It's AWESOME that you guys put in enough attention to detail, that you're using the colonial era flags (at roughly 2:10), rather than the national flags we're used to seeing today! It would have been really easy to half-arse the whole flag thing, so I'm really glad you guys put in the effort to represent them properly.

[@SirCharles12357]

I read Longitude by Dava Sobel; the most amazing thing to me other than the relentlessness of Harrison was the politics and backstabbing competition among the other inventors of the era. Fascinating book!

[@MrGregoryKershaw]

MAP MEN MAP MEN MAP MEN MAP MEN!

[@beaclaster]

map thing men

[@Ails1234]

Thank you, the subject was so familiar I was thinking this video was a reupload

[@kaXpi420]

WHEN WHEN WHEN WHEN WHEN

[@Mr._Dooter]

Isnt it like MAP MEN MAP MEN MAP MAP MAP MEN MEN

[@Wolfiyeethegranddukecerberus17]

MAP MAP MEN MEN

[@lajya01]

You should do a follow-up video on the history of the time zones. It has to do with trains instead of boats.

[@laurendoe168]

In the USA anyway.

[@Beryllahawk]

I find myself humming "Time is On My Side" now, and I don't quite know why... Fascinating bit of history! VERY cool!

[@siriusgd4753]

A few years ago I read the book "Longitude" by Dava Sobel. That book covered what you covered but it also covered all the other ridiculous methods that sailors were using at the time. The prize was never paid out.

[@davidkeenan5642]

Oh the prize was paid, but only after the intervention of the monarch. Harrison died a wealthy man.

[@seattlegrrlie]

Accurate clocks are taken for granted. You can buy them on the cheap. They'll even auto update. But time telling was huge and I am still amazed that this little trinket on my wrist can tell me what time it is

[@davidsoule8401]

A. That was awesome. B. Love the stronger humor element in this work. And the use of the slightly Terry Gilliam-esque animations. And then you did the ‘tik-tok’ joke… You’d probably make a great dad. 😉

[@jollyfish84]

We did a tour when we visited Greenwich in 2016 and there was this lovely retired professor taking the tour who was amazing to listen to and showed us all the different clocks (some were reproductions) that were made for the prize. While I have an interest in cartography I'd never fully understood how it all worked and it felt like a hundred light bulbs going off as all the lines got connected!

[@Mr.Anders0n_]

I know how John Harrison became such a good clockmaker. A time traveler gave him the design that John himself made in the future.

[@captainjirk9564]

The diagram of the north star really helped me understand how we found latitude! It makes much more sense now

[@DruNature]

I love this channel! Keep it up Joe, really a gem on youtube! I always get the feeling these vids are made for kids, but It just makes me feel like a big kid, and I love the rebrand, it is more grown up for sure!

[@asihiphop]

More than any of the information I learn here I’m genuinely blown away with the quantity of puns you think of for every topic

[@s-codes14]

The tick tocker joke got me 🤣.

[@OMJ_the_Show]

I love videos like this that explain interdisciplinary concepts and how in everyday activities. This is true education.

[@kellydalstok8900]

Four generations of the same family sold people the time. From 1836 up to 1940, the Belville family, most famously Ruth Belville, sold the time by going up to the Greenwich clock, the only timepiece which accurately kept Greenwich Mean Time (GMT), set their watch by it every week, and would then sell people a look at their watch so that other could set their watches accurately. Businessmen had a subscription to the business. - From QI Series G, Episode 15 - Green

[@CorwinFound]

Me muttering at the screen: Just use a clock. Come on people, this is not that hard. Be Smart: Clocks sucked Me: Oh. This got harder.

[@andor_yoko]

At 12:35; you need at least 4 to accurately get your location (to solve the linear problem with 4 variables _x,y,z_ and the variable time _t_ ). However to get quicker results your device often uses more than 4 signals.

[@eliljeho]

I was more disappointed that the clocks also have to take into account the relativistic speeds they are traveling (not near c, but it's enough, and their altitude is also messing with the effects of gravity on time.

[@timseguine2]

You only need 3 signals if you already either know your altitude or have accurate topographic data (and assume you are on the surface of the planet).

[@andor_yoko]

@@eliljeho Yes, both special and general relativity affect the timekeeping between the sattelites and the earth's surface.

[@andor_yoko]

@@timseguine2 That is right, your altitude information basically solves/gets rid of one variable. However, I wonder how you can get Your GPS to know the altitude. Or is that only a feature on some devices?

[@timseguine2]

@@andor_yoko As far as I know, the GPS units that support it assume mean sea level, which is a fairly crude approximation.

[@funlover1977]

3:53 Nope. A small correction there. It takes about 23h56' for its full revolution. Basically about 4 minutes less from what we normally call a day :)

[@olivier.st-amand]

Great video! If you wanna do a follow-up, you should explain how speed and gravity affect the time on those GPS satellites (because of relativity!).

[@tonysmith5465]

Very very outstanding video. Great job. Keep up the good work. Thanks a lot friend. SC Navy vet 1965.

[@Maybachdemon]

Can someone tell me what the zord/robot-thingy is at 1:14 next to the globe?

[@SANDWICHvanquish]

Thats Voltron

[@SANDWICHvanquish]

Is pretty cool

[@Maybachdemon]

@@SANDWICHvanquish Thanks! Really appreciate it. I recognized it from somewhere, but couldn't remember which show

[@SANDWICHvanquish]

@@Maybachdemon your welcome happy to help ^_^

[@SylvainDumazet]

One way we could have used, that is technically easier to do than precise mechanical clocks but needed the appropriate knowledge, is using radio-transmition to broadcast the reference time (using relays to cover all the globe). That idea is described in the book How to Invent Everything, by Ryan North.

[@alexrossouw7702]

Why am I not suprised that the humble clock gave Britain her seafaring edge

[@nerd_alert927]

3:09 😆 🤣 😂 Man, I love all the jokes/puns these videos always have.

[@jimbert50]

How did they accurately know the local time? Seems like just reading the sun wouldn't be very accurate.

[@stocktonnash]

they sacrificed a child and waited for it to rain. then that’s 3pm.

[@ziploc2000]

It is accurate when you use a sextant.

[@randomname7321]

@@stocktonnash YES

[@c.augustin]

As far as I know you make several measurements (with a sextant) before and after noon. Problem is movement (not good on a ship), but it works on land (astronomers did it "back then") …

[@MattH-wg7ou]

This is one reason a COSC (Contrôle Officiel Suisse des Chronomètres) AKA "Certified Chronometer" rating is so valued by watch collectors. 🙂 And as a Rated Navigator and watch nerd, I love this stuff! You did a great job of explaining it.

[@etownshawn]

the jokes in this episode were top notch

[@LarryB-inFL]

@0:42 Knowing where you are does NOT depend upon knowing WHEN you are...that is only true with the methods that were used involving astronomical objects. GPS does NOT depend upon what time it is, though it does depend upon measuring small time differences.

[@whereami8224]

Your GPS receiver needs to know where the satellites it is receiving signals from are. This is known from models of their orbits, and GPS time is the input to those models. Once the satellite positions are estimated, then the deltas in received times are used for the multilateration to determine the receiver coordinates. The GPS satellites and the ground stations operating them all have atomic clocks aboard, so I'd say accurate timekeeping is a pretty critical component to the system.

[@thetaleteller4692]

This Globe should be from around 1990, because Germany is already united and Yugoslavia still exists as a whole.

[@kirk001]

I've been wondering about 0 degree longitude all my life. Great to finally find out how that came about. Thank you!

[@DanSkunk]

It's about time! :P

[@mfaizsyahmi]

We actually don't use GPS timing that much in our daily lives. We instead use Network Time Protocol that uses the Internet to infer time from several Internet servers connected to really accurate clocks. If you're always online or on a network, wired or cellular, your devices will have access to NTP.

[@YouseTuber16]

Some stratum 0 time servers get their time from GPS.

[@dalehagglund]

As far as I understand it, the timing signals from GPS satellites are critical for actually computing your location, so I think they're used every single time you use your phone's location services. My assumption is that the use of GPS time for stratum 0 ntp servers is a clever re-use of data already present in the signal for another purpose.

[@sueelliott4793]

Very informative, we have been doing this research in Early Childhood Education in New Zealand in Māori vs Western technology and sciences in history. Teaching degrees are not for everyone but I'm loving it.

[@cmel7841]

What I find fascinating is universal travel, will people on Mars still calculate based on time back on Earth? I know they do now, but will that be the case forever?

[@gianluca.g]

I don't think so. Timezones don't make any sense far away from Earth. I think we'll use some distant, periodic event, like a pulsar or something.

[@stephenmorton8017]

best cup of coffee lesson ever. Lewis and Clark had an astrolabe. it was pretty much the whole point of the expedition. to get bearings on major waypoints and geographical features. they always need clear skies.

[@ringoffire0]

Did I miss something? How does one figure out the time of day where they’re currently at to be compared to the Greenwich watch? Is something like sunrise always at the same time of day?

[@ericfoster5331]

Yeah, I also had the same question. The only way I can think of doing it is to use another clock and set it to noon. Since presumably noon would be where the sun is highest in the sky. But that might not be the right answer.

[@brando8997]

Sailors could calculate local time based on the suns position with a sundial or also from the position of the moon, pretty accurately. But the video doesnt make that part very clear.

[@nulious]

by measuring the position of the sun with a sextant.

[@brando8997]

@@nulious sextant was invented in 1759 so they didnt exist in the period that the video is about.

[@nulious]

@@brando8997 before the sextant they used an astrolabe

[@petermarschall2637]

1:43 disclaimer: this globe ist not from the 1980s. Germany ist united, and that only happend in octobre of 1990.

[@sciencenerd7639]

Next pet I get is gonna be named Sir Cloudesley Shovell

[@scootergem]

You are having way too much fun making this as I am having tons of fun watching. Good informative Chanel and fun to watch 😁

[@CaptFoster5]

Wait, what? You mean we don't live on a pizza? Nooooooooooooooooo

[@katarinajanoskova]

If you ever visit London, try not to skip Greenwich. Get there on a boat (Uber boat or otherwise) and explore the market, the riverside, the beautiful park, the museums, and of course the Royal Observatory which is full of awesome things, many versions of the clocks, a fantastic camera obscura room and stunning views!

[@sstevocamaro]

Thank you to the creators of navigation

[@gabrielfrance91]

I think I've spent too much time on youtube 2:15 "Speaking of navigation" I was ready to skip the nord vpn ad lmao

[@stocktonnash]

Kyrie has entered the chat

[@ffff3c]

At 8:20 it's mentioned for Team Almanach "I check my local clock". Wouldn't that require a... precise clock? A more accurate explanation would be: - Team Alamanach: Figure out Greenwich time through a globally visible astronomical event, figure out local time using celestial navigation (eg sundial) - Team Clock: Figure out Greenwich time using a clock, figure out local time using celestial navigation

[@timseguine2]

Someone should found a hiking club on those islands and call it the Ministry of Scilly Walks

[@CommanderCodyCc--gh8zh]

"It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to."

[@Maffoo]

The "nowheresville" that John Harrison was from is the village Foulby near Wakefield in Yorkshire. There are places other than London! A great, informative and entertaining video nontheless

[@evlinalw325]

Can’t say enough times how much I love this channel and our wonderful host! 10/10 as always

[@h7opolo]

always fascinating to learn the stories of inventing something to solve a particular problem.

[@DracarmenWinterspring]

3:54 - that's 24 hours for the sun to return to the same position in the sky, IIUC if you want to use the stars you'd need a sidereal day which is slightly shorter (because we move around the sun so it's at a changing angle relative to the stars) 4:32 - except if you look that up you get the place's timezone, which is at best a rounded approximation of the "real" (sun-is-highest-at-noon) time you'd need for navigation (and in many places the shift is bigger than half an hour to e.g. keep a whole country in one timezone, not to mention DST existing/not existing and changing at different dates in different places so you could be off by an extra hour...)

[@carlosvergara4132]

This is a comment for the algorithm.

[@antonsimmons8519]

"Au-some" Worthy of its own upvote, frankly.

[@jmchez]

You should have given a shout out to Dana Sobel. Her best selling book on the subject, "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time" (1995) is now, the main reference on the subject. Also, everyone should watch, Tom Scott's video, "Why The Prime Meridian Isn't At 0º".

[@MrOvergryph]

Sharing this everywhere. Great stuff as always!

But... in 12 days of fog it would still be useless, as they wouldn't know what the local time is

[@orsonmoniz]

i guess theyd know the longitude just before entering the fog, and then they could estimate it further based on their trajectory which theyd know with a compass maybe? 12 days still feels like a stretch though. Also latitude would be difficult in a fog without access to view the north star.

[@nulious]

local time is set by measuring the position of the sun with a sextant.

@@orsonmoniz exactly this was their problem in that example, they lost track and had way too big error

@@nulious yeah, if you can see the sun

[@TheSwauzz]

When the aliens came up, I simply nodded along like "yes, yes, that makes sense" before I realized what was going on. 😅

[@AsmodeusMictian]

I eagerly await the FlEarth community's rebuttal on this obvious travesty! Everyone knows we're on a giant space pizza and all this 'navigation' stuff is just made up hooey! I mean, I saw it on YT so it must be true, right? ;-) Seriously though, I wish they'd show up on videos like this to 'disprove' them, I'd like to see how they attempt it. Given the last time that community tried to disprove the ol' 15deg drift.....

[@catfree]

9:52 Motion on the ocean causes a commotion

[@sumansharma1083]

Nice video broo keep going

[@SANDWICHvanquish]

First reply

[@dylanhenson7146]

Last reply

[@erichbaumeister4648]

12:46 - It isn't "three or four" satellites necessary to locate your position. It's four: 1) The loci of all points equidistant from one satellite is a sphere; 2) The loci of all points equidistant from two satellites is a circle; 3) There are two points equidistant from three satellites; 4) Location resolution. You're welcome.

[@OmShankar]

Justice for globey... A globe is more than it's latitudes and longitudes It's navigated its journey on this channel so far without them

[@melonmelon2848]

We gotta make sure to call out Joe if we no longer spot Globey in the background for future videos 😂🌎

[@JWentu]

One name of course, before even starting watching the video: Dava Sobel. Sobel's book about Longitude was a wonderful read and I highly recommend it.

[@the.arbiter8039]

Your backup globe must be pretty old, as there are no eastern Europe countries there xd

[@besmart]

Shh no one will notice Yugoslavia

[@micahbirdlover8152]

@@besmart first big tik toker that's funny 🤭😃

[@erodgenator]

I dig the genius editor of these shows! Right on! Well done!

[@daniellanctot6548]

All that and you didn't even explain what exactly about Harrison's clock made it suitable to the task? That's a big red *F* for this presentation!

[@maksphoto78]

It's enough to know that it kept precise (enough for those times) time while at sea. How exactly it worked is a topic for a separate video.

[@besmart]

If you want a video about advanced metallurgy and spring technology you'll have to go somewhere else, friend 😂

[@elainechubb971]

This is not totally scientific, but briefly, Harrison had already built extremely accurate (for his time and even later) land-based clocks. His experience as a carpenter using different woods helped; he realized a big problem was that metals, including steel, expand and contract with temperature fluctuations, distorting the timepiece parts. He was able to come up with a way to compensate. He also found a way to "cushion" his clocks and chronometers for use at sea from the movement of the ship on the waves. He was a very intelligent man, and his common sense and inquiring mind proved to be more useful than the university studies of the experts who were trying to refine the tables that were the competing and more prestigious system. I think he must have had a Darwinian type of mind, making observation primary and basing theories on actual facts. And, of course, having endless patience to keep experimenting over decades. One interesting point: a patron of Harrison was able to gain the interest of George III, who was fascinated by clockwork and automatons. This king tends to get dismissed as mad and/or a tyrant, but in fact, in the early part of his reign, was fairly enlightened as far as science and the arts were concerned. His interest and even help was useful to Harrison.

[@micahbirdlover8152]

@@besmart cool video 😎

[@aeroturner]

I LOVE these videos. Explaining things you never even thought you needed explained.

[@SioxerNikita]

51 seconds... I got pretty close to release time :9 And 8 views

[@danielcamejo1177]

Excellent, simple 😮scientific explanation of longitude. Should be used in schools worldwide.

[@KwakWack]

"See you next time, wherever that is" is such a badass sentence and even better after watching this video

[@heronimousbrapson863]

I believe up until the early 20th century, different countries used their own origins for longitude; France used the meridian of Paris, and Imperial Russia used a meridian passing through St. Petersburg. Eventually, they converted to the Greenwich convention.

[@RichardFerreria]

OMG I've always wanted to know why the Prime Meridian goes through Greenwich! Thanks for enlightening us once again

[@paddington1670]

My family originates from the Scilly isle. There are more shipwrecks there than anywhere else on the planet, and thus it is the most archaologically significant per square kilometer than anywhere else in England. There was one ship that wrecked that was carrying beads and they named the area beady poole because there were so many beads on the beach. You can even still find beads if youre a really lucky tourist, but my grandmother had an entire necklace of them, that she split up into 4 small not necklace strands and gave them out to my aunts and my Dad. Im related to almost everyone buried in the church cemetery on St. Agnes, my grandmother told me that they stopped marrying their counsins "just in time." it's a family joke. They were lighthouse keeps, rescuers, and brandy smugglers from France where they could out row the coast guard sail boats. They still have gig races among the islands. basically just big row boats with lots of people, like our Canadian dragon boats. Hard times were had by the people in the Scilly isle, my Dad told me some years they only ate seaweed and my family's overall life expectancy is lower than others because I have impoverished genes from centuries ago of hardships - I lold a bit, but ok. There are also warm currents that run past the Scillies and it feels weird to feel Californian air off England's coast, and seeing somewhat tropical plants on the island is a trip. If you visit, pay extra and take the plane, my cousin Kate told me the 3 hour ship ride out there is terrible and youll get sick

[@turcenoarthurjamil4364]

Its already complicated enough for ordinary people to comprehend this, now imagine what seafarers do, especially the 2nd officer or the navigation officer. Its so complicated and hard it required your utmost concentrations just ti calculate or plot your position correctly. Thanks to modern technology it now makes our job a bit easier. Saludo sa lahat ng mga marino🇵🇭⚓🚢

[@ilghiz]

9:55 Is it motion on the otion or mocean on the ocean?

[@shawnholbrook7278]

Thanks for the awesome and "timely" videos! 😁

[@chrishayes9855]

I honestly (until right now) thought of 0 degrees as a product of "the world revolves around me" thinking. Now it's more like, "This is how we made the world revolve around Greenwich." It actually earned its place.

[@adrianneosa1490]

"I'm gonna mark so much territory" Also, I love how they painted the dog with a wig. Classic British haha

[@jmalmsten]

I am very much looking forward to the follow up video "Where is when"

[@honkhonk8009]

11:30 Its also how America won in Iraq. GPS allowed US M1 Abram divisions to cross sections of desert which was considered impossible to navigate, and thus wasn't defended by Saddams generals. GPS was also what allowed a lot of cruise missiles and such to work, when originally these cruise missiles would only use odometry. location is a really valuable service

[@garybarnes4169]

01:39 specifically right through the middle of the eyepiece of a telescope at the Royal Observatory, because, well, they did a lot of observing.