Sextant to Line of Position - A Complete Sight Reduction from an Offshore Sailing Race
ฝัง
- เผยแพร่เมื่อ 19 มิ.ย. 2024
- I recently returned from a sailing race and along the way I took some Sun Sights using a sextant with my friend Chuck. In this video, we will reduce one of the sights from beginning to end. We'll cover all the celestial navigation theory and math required to take a sextant reading to a usable line of position on a chart.
The five main steps are:
1: Observe and correct the sight.
2. Find the geographic position of the sun.
3. Build a spherical triangle.
4. Solve that triangle using formulas or HO229.
5. Compare the computed value to the observed value and plot it.
This sight reduction uses the St. Hilaire method of altitude/intercept. It also relies on the Nautical Almanac and HO229, both of which are available for download from the internet for free.
Nautical Almanac and HO229 available here - www.thenauticalalmanac.com/
For more on celestial navigation, you can refer to other videos on this channel, specifically the 11-part celestial navigation series from 2013 (starting with Getting Starting in Celestial Navigation).
- • Celestial Navigation (...
For free and discount marine navigation courses, visit www.practicalnavigator.org. Thank you for your support!
Time Stamps:
0:00 Introduction
0:46 General Navigation Background
5:23 Using the Sun as a Lighthouse in the Sky
7:10 Geographic Position on a Curved Earth
10:07 Celestial Navigation Theory - Circles of Position
13:30 Step 1: Observe and Correct the Sight
29:05 Step 2: Find the Geographic Position of the Sun
39:46 Step 3: Build a Spherical Triangle
49:14 Step 4: Solve the Triangle
53:57 Step4A: Direct Mathematics Solution
55:25 Step 4B: HO229 Solution
1:01:34 Step 5 Compare and Plot the Solution
1:11:29 Review and Conclusion
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Chris, you are a master educator. This is the best instructional video on celestial. Period. You are to be commended.
Wow, thank you for the kind words, sail safe!
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You are simply the best tutor in this field...absolute GURU.... thank you for your brilliant work !
Some really smart people figured this out. Especially those in olden days. It blew my mind just watching this. Great job explaining but WOW.
I searched how the stat tracker on the SR-71 worked... It's been quite the rabbit hole and now here I am!
That was without doubt the best explanation I've seen so far and the order of flow very well presented.
I have take a course on navigation but haven’t yet used it ‘in anger’. Your video is a fantastic refresher course for this. Thanks very much!
Haha - nothing better than angry celestial! JK I get what you are saying, thanks for watching!
@@NavigationTraining doing something In Anger is a British saying for using it for real 😂
Definitely the best video to understand celestial calculation, master class 👏👏👏 thanks so much Chris🙏
EXCELLENT instruction Chris. I have a lot of difficulty going from printed material only to comprehension. This just clarified a lot and I will save this vid for ongoing reference. I'm hoping to be a student of yours at some point in the near future. Mahalo!
As always,.... Brilliant explanation... enjoy everyone of your easy to understand yet professional videos... and enjoy the subtle humour too!
Excellent…..am back to my sextant after many years, great refresher! Thank you, Andrew
This is definitely the best introduction to celestial navigation video I have ever seen! I first got into learning celestial navigation through your videos. I bought myself a Davis mark 15 and an artificial horizon, and I'm hooked. However since for me it's just a hobby I haven't invested in a yearly nautical almanac and a full copy of HO229. Instead I got the 50 year nautical almanac by Geoffrey Kolbe which include concise NAO sight reduction tables. It's a lot more math and corrections but for me it seems to do the job. I would love to see a video on your thoughts about using the 50 year almanac and NAO tables, because for beginners like me a single small book is a tempting alternative to a huge yearly almanac and full set of HO229.
Thanks for the kind words Keenan. I get what you are saying about the single book, we all learn different ways and I grew up with HO229 and the Nautical Almanac. Luckily both are free downloads so you can just get the pdf versions!
Hi Chris You've really opened my eyes, I've studies online courses and read books on this subject in the past but it largely remained a mystery. You are a very skilful communicator and educator and you have really helped me consolidate my understanding on this topic. Many thanks Chris.
Thank you for the kind words Adri!
Chris thank you for condensing it down this is one of my all-time great videos on Celestial Navigation a keeper cheers
Glad it was helpful!
Thanks Chris. Brushing up on my nav. This video has saved me hours. You are the best.
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Hello sir! Im an avid fan of yours. I already watch all your video clips about celestial navigation when i was a cadet. Now its nice to see your videos again with great and step by step explanation. Sir i would like to see a celestial calculations when you are in the EAST hemisphere. Hope to see more videos like this. Keep it up sir. God bless!:)
Thanks for all your videos.
Great stuff! I saw your original videos and decided to learn Astro. I used the RYA online course but to be quite honest, your explanations both in the original videos and this lecture are far better presented. I'm about to go sailing and put it into practice and I will definitely watch this video again before hand.
Cool, thanks!
I'm not sure how it could be any better, the video. I really understand the procedure after only a few small rewinds. Thank you very much. I'd donate a bit if I could.
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Very good explanation!
Glad it was helpful!
Thanx mate for explaining.. Studying from books just can't help much but your practical way of explanation is wonderful... I noticed you have lost many hairs 😄😄..same like me but now I did hair transplantation and back to my early days...
Simply brilliant.
Chris’s original video series was instrumental in my learning celestial navigation. As someone with zero previous understanding of the fundamentals of celestial mechanics, I needed to put in a lot of extra research in order to understand celestial nav. It was a very interesting journey, and I’m very grateful. Thanks much. I liked solving your code above the whiteboard as well.
Awesome thank you for the kind words!
Thanks for an excellent presentation:)
Thank You! Very helpful.
You're welcome!
Beautiful beautiful beautiful celestial info.
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Excellent teacher.
thanks.. super explanation
Great video!!! Thank you.
You have a gift for very subtle and amusing humor.
Thanks for watching! USCG, nice acronym haha.
Your great teacher thanks,
long, necessarily so, but wonderfully clear!
I never had a chance to learn Celestial Navigation from an expert, I had to teach myself! But even back then, the 50's and the 60's, there were some excellent books on the subject. I still have an ancient copy of "Mixter" that I used when I was first getting started.
Keep up the good work!
The "Art and Science" of Navigation must live on.
Just find the Kevin Spacey looking guy for quality CelNav tuts. But in all seriousness this was excellent in just about every way. I'll be looking into that 11 part series you mentioned. Instant sub.
You're amazing!❤
Thank you
What an eye opener. Spherical concept aside, the practical use over a plane was a treat to learn from you. Thank you very much
excuse me but when did he suggest in any way that you can find your position using a planar earth?
@@bacon3423 did you watch the video? Lol
yes, that's why I'm asking. so, can you point out when is it?
@@2Storyz nothing?
@@bacon3423 watch the video again
Just outstading!
Chris thanks for the video learned alot, I am refreshing my Celestial skills and knowledge and your videos are really life saver for an aspiring officer like me. Just one thing bro, believe me I hate to say this but thought you might wanna know the greek letter or symbol for Longitude is phi (φ) and for Latitude is Lamda (λ). I always confused these symbols when logging onboard but felt curious about it so I did a quick google search.
Thanks John, I use marine navigation terms such as this link: wiki.gis.com/wiki/index.php/Longitude
Thank you!
Thanks
Phenomenal video. The best celestial video I’ve ever seen.
Chris, thanks for the very clear explanation! And yes the earth isn’t flat here in the Netherlands either😏
I dunno, the Netherlands always looks pretty flat to me 😛
Have you ever seen the north pole or south pole
@@umahlekisa You can travel to either if you wish.
@@marcg1686 every one in cape Town wishes to go south but no. 🇷🇺 military enforces the treaty. No games
@@umahlekisa Everyone? I find that difficult to believe. Fly to Argentina. There are Antarctic expeditions starting from Ushaia.
Thank you for your introduction this topic very nicely. Because as a Deck Cadet I always was worrying about celestial navigation. After this video I believe that I will handle all of it. May I ask that what can be the maximum acceptable Nautical mile away or near to the sun for ocean passage
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Excellent instruction. Thank you. I have two questions for you sir. Q1: I understand how you corrected Hc for the declination being between 21 and 22, but why did you not correct the Azimuth angle for the same reason? (Because the Azimuth also changes from 21 to 22). Q2: How many miles of error between Hc and Ho is acceptable? I'm curious how awful I can be with my assumed position.
About 30 miles from HC to HO should be maximum if you are on the right track with your reduction. To be totally correct, you should correct the azimuth, but in practice it is usually so small (less than 1 degree or so), that it is taken up by the thickness of the pencil on a chart. But you are totally right for theoretical solutions, great point!
Chris. So new to this subject that my sextant purchase has not even arrived yet! I wonder if you would comment on the following thought relating to your sight reduction solution (Step 5): With GP Sun ~due west of DR, the LOP would be a strong fix for Longitude but a poor one for Latitude (which has not improved from the AP N32 deg). Is that right??? Is something else required to refine Latitude for this example? I was hearing that a compass bearing extended over a long distance is not sufficiently accurate? (OR am I missing something altogether?) Like many people, I have found your videos extremely informative - many thanks!
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Hi Chris! I would really appreciate it if you will answer my question. Way back in school days, we were taught to do the equidistant projection, orthographic projection. In actual practice, are these projections necessary? Thank you in advance.
Yes, they are important, but not so much for celestial navigation as they are for general navigation and route plotting. On a Mercator's projection, compass bearings are straight lines, useful for coastal and offshore sailing. For longer distances, a great circle route is desirable so a Gnomonic projection is used. Various other projections are used for geographic and political representation so that land areas look approximately correct as Mercator's distorts areas near the poles, e.g. Greenland.
Great video. 30+ years ago i studied CN with an instructor from the Naval Academy and became ok with using it and haven done it in many years. My question please, at about minute 39.09 you added the conversion of GHA and arrived at 121 903’. Then converted it to 122 303’ due to 60’ in one hour…..how did you arrive at the conversion to 122 303’? Thank you
'Then converted it to 122 303’ due to 60’ in one hour…..how did you arrive at the conversion to 122 303’? Thank you'
The time of the sight was 20:07:30 UT.
The GHA for 20:00:00 was 120° 37.8'
The increment for 07:30 was 1° 52.5'
which gives us 121° 90.3'
Subtract 60' and adding a degree to 121° gives us 122° 30.3'.
Hello from Brazil
Hello Walker thanks for watching!
Well done, as expected. I miss the flaming Astra. How many sextants do you own?
Thanks Wesley, I have the Flaming Astra 3B, the Cassins and Plath from the video, a Davis plastic sextant, and one more un-flamed Astra 3B. Just in case!!
Very interesting and informative video. I've tried to replicate your calculations using G. Kolbe's Long Term Almanac 2000-2050 (2nd Ed.). My GHA and Declination are very close but I'm getting sight reduction results, when using your video's calculations, that are off by about 6 minutes when accuracy, according to the book should never exceed a difference of 0.7'. I was wondering if you've had any experience with the Long Term Almanac and can explain why there's such a "large" discrepancy. Thanks.
Assume the earth is flat.
Assume the map are heavily inaccurate.
Try going towards the north pole and you will be lost.
Also for true knowledge on the sextant join the russian MOD and you will be good to go
Ditto to all the other comments. Really enjoy your videos. Just got myself a Davis MK15 and having a blast. Sadly I’m land locked, closest ocean is 14 hour drive away! I understand you can use a lake but how? Our elevation is 2818 feet. What do you think of the Practice Bubble Horizon (I think Celestaire makes them) vs an artificial horizon? To bad these (Professional Bubble Horizon) are so pricey and no doubt to heavy for my little plastic sextant. 😜
Hello, I think the most important skill to work on at the beginning is actually making the sight - ignore the math for a while and you can be at any elevation. Otherwise I do like the artificial horizon (you can also just make one from a pan of water). Finally, recommend looking into air-based celestial navigation regarding the bubble sextant, it would be helpful for you to see how pilots in the old days did the work from altitude. Thank you!
@@NavigationTraining Thanks a lot. Keep up the great job. Love how easy your instructions are compare to some I've watched! :))
so what u gonna do is to shoot and observe then do the mathematical equations fast to shoot again on that spot to check if your calculations is right?
I have a quick question about a small but potentially important detail. At 57:10 you state that In northerly latitudes, if our LHA is less than 180, then we have to take 360 minus Z in order to get Zn. Is that when our assumed position is in a northerly latitude? Or when the GP of the sun is in a northerly latitude?
Hi, if your dead reckoning is in the Northern Hemisphere and the LHA is less than 180° the bearing Zn is equal to 360° - Z.
LHA is only ever measured to the west and always from the observer to the GP of the celestial body.
Zn is always measured clockwise from N 0° true.
Thanks! I think these days we would use an App to solve the triangle, there are a few free ones around. Look forward to a video on those. Also, does anyone know of an App that can record voice and timestamp? It would be great to have one when you are taking sights, instead of having to scramble for pen, paper, torch!
Sight Calc on iOS just solves LHA, LAT, DEC triangles.
Just found Mark Time on iOS, just tap the screen to record time, you can then take a photo of the sextant numbers. I think it will be very handy indeed.
CelestialNavigation app from Harald Merkel on iOS for $1.99 seems good. It does everything covered in the video, including plotting, advancing lines of position, star charts. I reproduced a sun-run-sun fix from a 2018 trip to Madeira. Some care needed with inputting the correct sign for Index Error ( if you need to increase sextant altitude, you need to input a negative quantity).
if you recorded a bearing to the sun with your observation - couldn't that be used to directly calculate a circle of position based on sun's geographical position? fewer steps, but more error from bearing observation?
Hi Cameron, definitely - the problem is that you would need a chart of appropriate scale to plot that circle of position, which would then mean it is so small scale (large area chart) that your fix is not useful. You are correct about the logic, which is what the St. Hiliare altitude intercept method does to get you on a more useful scale chart. Thank you!
Do you turn the micrometer drum to left or right after sun kisses the horizon ?
Turn it in the same direction that you turned it when you read your index error. This way you do not create an additional error for backlash in the arc rack gear teeth.
@@youtubeleavemealoneEspecially if you're using a Davis Mk15 or 25. Generally however you should be turning the drum so as to increase Hs.
HO 214 AND DRIENSTOCK HO208 FAN HERE !
Old school, love it!!
Hi there! Great vid. In your triangle diagram at timestamp 4:22 can you maybe explain how you obtained a flat horizontal adjacent and a perfect right angle on a constantly curving globe earth with a curvature rate of 8 inches per mile squared based on the given 3959 mile radius? Thanks!
Look at the diagram - it is a lighthouse. Now maybe you have never seen one living under a rock, but they are only about 50 metres high, so at a distance of say 20 km, you don't need to worry about curvature unless you are surveying to an accuracy of 1 metre or less. He is simply explaining the idea of a position circle.
It's been two years since you clowns decided that a sextant can only be used on a flat earth, yet not one of you can demonstrate its use. Not even liars like 10th Man- who actually has one.
Mindless clowns.
LHA is important when you're trying to fit all of the tables required to do this into a single book.
No offence, but I don't understand the point you're trying to make.
If you use HO229 or HO249 Volume 2 and 3, the entry arguments are Lat, Dec and LHA. If you use HO249 Volume 1 the entry arguments are Lat and the LHA of Aries. The LHA is a prerequisite.
@@marcg1686 That is my point. With LHA you can constrain the number of possible triangles that need to be pre-computed down to something manageable. Very clever.
I have been looking for the mathematical formula to calculate the elevation angle from a curved baseline, do you have it?
sin(Hc) = sin(lat)sin(dec) + cos(lat)cos(dec)cos(LHA).
Lat is the latitude of the observer.
Dec is is the declination of the celestial body observed.
LHA is the local hour angle.
I know it's a problem for you flattards, what with you only having the attention span of a goldfish 'n all.
10th man can't help? Figures.
lol you took one look at that equation and ran away
@@iveneverseensuchbehaviorin5367 But he ran away bravely...FE style.
_''calculate the elevation angle from a curved baseline''_
Hey Rayleigh, we don't calculate the elevation angle from a curved baseline. Your papa flerf lied to you.
Navigation instructions always seem to boil down to "BUT A GOOD NAVIGATOR ALWAYS KNOWS THEIR APPROXIMATE POSITION". What do you do if you don't know your approximate position? What are you supposed to do if the "good navigator" dies and your GPS system goes down from water damage or an electrical malfunction? If you have non electronic back up equipment such as an accurate chronometer, a good working sextant, a compass, a pelorus , a book of trig tables or a calculator, and an up-to-date almanac, how do you navigate? There must be a way to accurately navigate without knowing your approximate position
Let's say you are on a journey from Chesapeake Bay to St. Thomas, and the navigator is snapped away by Thanos - you are left. You know you are somewhere between Chesapeake Bay and St. Thomas, and you can probably estimate about how far along the path you are. That's all I'm talking about. You know you are not near the south pole, or east of Hawaii or on Mars or something. Very approximate position is all thats needed. And if you didn't know that, you could figure out your approximate position easy with the equipment you mention. One noon sight gets you latitude, and your chronometer gets you longitude. Good question, I just don't want you to fixate on that part because the approx position is either known or easy to get with the gear. Thanks!
7:00 so um, is that to scale, bro?
Totally to scale, I measured twice!! Haha thanks.
Not flat earth, but flat. So oxymoron. Got it. No horizontal horizon on a sphere with no edges or vertices. Great video
Are oceans flat or curved?
@@robertlafleur5179 oceans appear flat as you look out to them. Sextants use a flat baseline. Try Euclidean geometry for once
@@FreddyKrueger-kc1sx Sextants don’t use a flat baseline, they only measure angles.
I know how to do celestial navigation, you don’t.
If oceans were flat why would you see a horizon, think about it
@@iveneverseensuchbehaviorin5367Thinking? You’re expecting too much of Freddy!
#Star Trail: Evidence the Earth is a Sphere
In the northern hemisphere, if we look at the sky to the north, we can observe stars rotate counter-clockwise around a point. This axis of rotation is not visible from observers in the southern hemisphere.
On the other hand, in the southern hemisphere, if we look at the sky to the south, we can observe stars rotate in the opposite direction. Conversely, this axis of rotation is not visible from observers in the northern hemisphere.
This motion of the stars cannot possibly happen in a flat-Earth.
#Stars in the Southern Sky Prove Earth is a Rotating Sphere
If we look toward the south at night in any location in the southern hemisphere, we will see the same set of stars. We will see the stars rotating around the south celestial pole, in the Octans constellation, near the star Sigma Octantis.
The flat-Earth model cannot explain the phenomenon. Looking at the so-called ‘flat-Earth map,’ we should see another set of stars on a different location in the southern hemisphere. The reason is that the flat-Earth model is a false representation of the Earth.
As an example, we will use five cities: Sydney (Australia), Papeete (Tahiti, French Polynesia), Santiago (Chile), Johannesburg (South Africa), and Jakarta (Indonesia).
If the Earth is flat, then observers on the different cities will face opposite each other, and therefore everyone should see different stars. However, in reality, they will see the same stars, only with different orientations. This observation is only consistent with the spherical Earth model and cannot be explained with the flat Earth model.
The flat Earth model was initially designed for the northern markets without much regard for what is happening in the southern hemisphere. Back then, it is difficult for those living north of the Equator to observe the southern stars, and it was not easy for most of them to confirm that the flat Earth model is nonsense. However, we live in modern times and do not have such an excuse, especially for those already living in the southern hemisphere.
en.wikipedia.org/wiki/Celestial_pole
en.wikipedia.org/wiki/Category:Southern_constellations
#Polaris Altitude from Multiple Locations on Earth
The angle (or altitude) to Polaris approximately corresponds to the latitude of the observer. This fact is observed on every location on Earth where Polaris is visible.
By tracing the path to Polaris from multiple locations on the flat Earth model, the lines will not point to a consistent position of Polaris. The reason is that the Earth is a sphere and the flat Earth model does not represent reality.
The position of Polaris today is conveniently very close to the north celestial pole. And therefore, the altitude or the angle between horizon and Polaris can be used to determine the approximate observer’s latitude.
South of the equator, Polaris is not visible and obviously cannot be used for navigation. Polaris is below the horizon and obstructed by the Earth. It is necessary to locate the south celestial pole in the sky to determine the observer’s latitude. It is more difficult as there is no bright star nearby, unlike Polaris in the north.
Polaris itself is not always the north star. Due to the Earth’s axial precession, the position of the north celestial pole will shift. Twenty centuries ago, the north celestial pole was closer to Kochab than Polaris.
All the observed facts are only possible if the Earth is a sphere, and impossible to happen if the Earth were flat.
en.wikipedia.org/wiki/Celestial_navigation
#Celestial sphere
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
The celestial sphere is a conceptual tool used in spherical astronomy to specify the position of an object in the sky without consideration of its linear distance from the observer. The celestial equator divides the celestial sphere into northern and southern hemispheres.
#Celestial poles
The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively.
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#Nautical Almanac
A nautical almanac is a publication that describes the positions of stars to enable navigators to use celestial navigation to determine their position at sea. Because the positions of stars are not fixed, a nautical almanac needs to be continuously revised.
Flat-Earthers claim that the positions of stars are fixed, and they only circle the celestial pole. In reality, stars’ positions do change, and we can find the historical positions of various stars from old publications of a nautical almanac.
One of the most well-known nautical almanacs is published by the government of the United Kingdom. This nautical almanac was first published in 1767, and new revisions are published every year. From different revisions of this nautical almanac, we can see the shift of the stars’ positions.
We often see flat-Earthers claiming that Polaris always stays in the same position. From a nautical almanac, we can understand that contrary to what flat-Earthers claim, Polaris’ position does change over time. In 1834, the official British nautical almanac gave us that the declination of Polaris is 88°25’40”. However, in the 1923 edition, it is 88°53’35”, and in 2018, it became 89°20’31”.
The determination of a ship’s position from celestial navigation depends on the accuracy of stars’ position in the nautical almanac being used. Because we do not have a fundamental problem in celestial navigation, we can be sure that the positions of stars being reported in nautical almanacs are correct. And therefore, we can understand that the change in stars’ positions is indeed occurring.
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archive.org/details/nauticalalmanac30offigoog
archive.org/details/in.ernet.dli.2015.90651
asa.hmnao.com/
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Assuming that you are using a sextant, you have an elevation angle of 50 degrees for the Sun as you are viewing it through the sextant. With the sextant horizon mirror, you bring the sun down to the horizon (sea level), mark the time when the sun just touches the horizon line, and use that time mark and degree to find out about the position of the Sun at a given time. If your eye level is above the sea level you have to do dip correction to the sea level!
It is in the book Navigation Almanac, which contains all the information about the position of all celestial bodies at a given time.
Okey, you have 50 degree siding (elevation angle) of the Sun and 180 degrees baseline following the surface or the sea level to the horizon,or GP (named ground position) That gives you 90 degree right angle triangle to the sun.
Now you subtract from the 90 that 50 and you get 40, 40 times 60 nautical miles, you're 2400 nautical miles away from the GP, to the sun.
It can never happen on a globe with radius of 3959 miles.
It's A circle of equal altitude around the GP, and means you have a flat area of 360 degrees, 2400 miles of equal altitude.
It is necessary to repeat the procedure 1-2 times so that your other circles of equal altitude can intersect one another. On the chart, it will show your position on the earth. Use it to plot your way! that's how celestial navigation is performed.
The known area of the earth is definitely Flat so far we know!
Well that isnt how celestial navigation works and you have sevetal flaws in your new way of doing it. Where do you get 60 nautical miles from? 60 nautical miles per degree is incompatable with a flat earth. The distances between lines of longitude wouldnt work.
Right angle triangles aren't used in celestial navigation, but if you claim we can make one to the sun then i feel bad for those poor people being roasted at sun set. Way to many holes, back to the drawing board.
@@iveneverseensuchbehaviorin5367 I am still waiting for Jon, Any of Joakley's disciples, or any other Flerf to show me the derivation of the dip angle corrections in the nautical almanac (which they all agree are correct) WITHOUT using the Earth's radius. Going on 2 months now and no takers!
Circles of equal altitude only work on a globe, literally on a globe. They don't even work on the charts that navigators use.
Why are there no maps available that show the flat earth?
@@marcg1686 OMG! Is it necessary for me to answer this nonsense? The surface cannot be spherical if there are circles of equal altitude over it!
@@JonBernhards66 I've an idea.
I'll post three observations with the GPs of the celestial bodies observed and you plot them on a flat map and post a photo of the result to your Community tab.
Think you're hard enough?
I learned that a sextant is not nearly as fun as it sounds.
The sextant itself becomes ho-hum fairly quickly. It's the sight reduction that follows that is most satisfying.
At 8:00 you misrepresented a spherical right triangle as they aren't ever depicted orthographically but rather on the face of a sphere.
Here's the maritime navigation reference, thanks!
thenauticalalmanac.com/Bowditch-%20American%20Practical%20Navigator/Chapt-21%20NAVIGATIONAL%20MATHEMATICS.pdf
@@NavigationTraining Thanks for the reference, regardless, the triangle you drew at 8:00 has two straight lines and a curved adjacent, this isn't a spherical right triangle and isn't what's represented within your reference. As previously stated they are only over drawn on the face of a sphere.
@@NavigationTraining Also see page 4 of your reference in the first paragraph under Trigonometry. "Spherical
trigonometry deals with spherical triangles, which are
drawn on the surface of a sphere".
I understand spherical triangles go on spheres - I guess I am missing main your point....how would you choose to represent this concept to new learners? Thanks!
@Practical Navigator
I suppose the concept you want to present here is what your colleague concludes at about 44:30 in his video th-cam.com/video/-ARXW8InStY/w-d-xo.html
So, how do you get right angles to GP on a “sphere”? Circles of “equal altitude on a “sphere”? Polaris always in same position on a “ball that flies at 66.6 thousand mph??? I assume you apply lots of mental gymnastics to make it fit your “spinning, wobbling, flying ball in vacuum” religion. I know it’s painful but,basic Euclidean geometry debunks your fantasy. Earth is experienced, measured and navigated Flat and Stationary.
Thank god you’re here Vlad!
All those poor navigators of years past that didn’t know what they were doing. I wonder how they managed navigation when they didn’t have TH-cam to read your comments.
@@robertlafleur5179 Like I said, I know it's painful but, maybe you deserve the cognitive dissonance and pain you're experiencing. You didn't respond to any of my points, and your response is typical of a cult member and a triggered and ignorant person. You ridiculed and exposed yourself for your ignorance and cultish behavior. Navigators of "years past" navigated the same way as they always did, and still do today - they used sextant to get "elevation angles" but, they just did NOT have to imagine the supersonic globe and invent maths to "explain" it to non thinkers and cult members like yourself. They knew that Angles are two Straight lines meeting at a vortex. They knew that to have 90 degree angle to a GP of a star a flat baseline is required. They knew that circles of equal altitude are equal elevation = Level. Flat Earth is required to perform celestial navigation. Get it? I doubt it but, there it is anyway. Now tell me again about your feelings and what you think of me, you poor thing,...just please don't hurt yourself.
A star's GP is too complicated for you? i believe you. Circles of equal altitude too complicated for you? i believe you. You dont know polaris has movement? i believe you. You dont know stars are far away? i believe you. I hope someday you gain the intelligence to understand these things as many people already have.
@@Vlad_on_Zero_DegreesCognitive dissonance, pain, cult member, triggered and ignorant person, non thinkers; are you projecting Vlad?
I am in no pain because I understand celestial navigation but it’s painfully evident that you don’t. Let’s see:
Navigators don’t use that ‘’90 degrees angle to the GP’’when they measure the elevation angle to a celestial body.
They calculate what would be the elevation angle if they were at the AP (Assumed Position), this is where they think they are. It is NOT the GP.
They also calculate the azimuth (Z) to the celestial body.
These two calculations are made using SPHERICAL trigonometry. Does this ring a bell? Spherical as in sphere, globe, ball.
They then compare the sextant angle (Ho) with the calculated angle (Hc).
If Ho is larger than Hc then they are closer to the GP.
If Ho is smaller than Hc then they are farther away from the GP.
The AP is plotted on a plotting sheet (a sheet of paper with a few local latitude and longitude lines)
The distance in Nautical Miles (NM) is measured from the AP toward or away from the GP along the azimuth and a perpendicular line to the azimuth is drawn.
That perpendicular line is the Line Of Position (LOP). It is a very small part of the circle of equal altitude and as such can be drawn as a straight line.
The same operations, sextant angle, calculated angle, AP, drawing LOP, etc is done for another celestial body. Where the LOP crosses is your fix, your position.
Nowhere did the 90 degree angle at the GP came into play. The GP does not appear on the plotting sheet as it is usually thousands of miles away. A flat baseline is also not used as there is no flat baseline.
I didn’t hurt myself, thank you for worrying about me.
Now please explain celestial navigation on flat earth, Vlad.
@@iveneverseensuchbehaviorin5367Vlad doesn’t understand celestial navigation, he’s an ignorant. That’s ok.
The problem with Vlad is he’s an arrogant ignorant.
The sun cant change in size if 93,000,000 miles with just a simple 23.4° tilt.
Nobody said that.
@@robertlafleur5179 so the sun isn't 93,000,000 miles away
@@FreddyKrueger-kc1sxNobody said that the Sun at 93,000,000 miles would change size because of Earth’s tilt of 23.4 degrees.
The Earths orbit around the sun is an ellipse, not a perfect circle.
@@robertlafleur5179 heat
Русские, этого нам никто и никогда не простит. За эти три дня весь мир будет смотреть на каждого из нас, как на прокаженного. Делайте выводы сами что надо делать!
It's not flat "really" oh yes it is.
Your brain is flat
You live on a globe with a mean radius of 3440.1 nautical miles.
No, its not flat. Watch the video.
If I had to sit in a class to listen to this , I would have fell asleep pronto , why do teachers take the effing long way to explain something , the sextant definitely not gunna be in my tool box after watching this , bored me to tears.
The sextant not being in your tool box is probably a good outcome for everyone.
Learning is hard for you 😢
@@jeffreycraig4556 So true. 😅
th-cam.com/video/PGEDbhGAvaI/w-d-xo.html
@@Vlad_on_Zero_Degrees Another video by Oakley, the guy who can't do celestial navigation. Tell him that he lied to you.
Didnt understand anything
th-cam.com/video/PGEDbhGAvaI/w-d-xo.html
That's OK. The others did understand.
The Earth is Plane and Stationary.. we checked. Thanks
Then check again. You're living on a spherical earth with a radius of 3440.1 nautical miles. We orbit the Sun.
It's round. I checked. Have you?
@@Earthislife1031 where have you checked prove the earth is moving under your feet
@@TheIsmaelIsaac Foucault’s Pendulum Proves Earth is Rotating Sphere
Foucault’s pendulum proves Earth’s rotation. In the Northern Hemisphere, the pendulum rotates clockwise. In the Southern Hemisphere, it rotates counterclockwise. The pendulum turns faster if it is closer to the pole. On the Equator, the pendulum does not rotate.
Flat-Earthers invented various excuses to discredit Foucault’s pendulum. In reality, anyone not near the Equator can easily repeat the experiment, and it will give the expected result.
The Foucault pendulum will rotate with an angular velocity of 360° × sin φ per day, where φ is the latitude of the pendulum’s location. It rotates clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. There is only one explanation for why Foucault’s pendulum behaves like that: the Earth is a rotating sphere.
#Foucault Gyroscope
In 1851, Léon Foucault used a pendulum to demonstrate the rotation of the Earth. Despite his success, he was not fully satisfied with the pendulum experiment because of the dependency on the sine of latitude, which the public found difficult to understand. He later designed a device which he named ‘gyroscope.’
A spinning gyroscope keeps a constant axis of rotation in space, so it should slowly rotate with respect to an observer attached to the rotating Earth. The challenge was technical; it would need to have minimal friction, and it has to be able to spin for a sufficient duration so that the precession due to Earth’s rotation can be observed.
Gustave Froment helped Foucault to build the device. Using a hand crank and four stages of gearing, the gyroscope can be launched with the initial speed of 12000 rpm, allowing the rotation to persist for 10 minutes. It was sufficient to observe the precession due to Earth’s rotation, using a microscope.
www.sciencedirect.com/science/article/pii/S1631070517301019#br0110
tobin.fr/foucault.html
www.prc68.com/I/Gyroscopes.html
#Ring Laser Gyroscopes are Sensitive Enough to Measure Earth’s Rotation
A ring laser gyroscope (RLG) is an instrument for measuring the change in orientation and rotational velocity. It is sensitive enough to measure Earth’s rotation easily.
Flat-Earthers claim that there is no instrument able to measure Earth’s rotation. Such claim arose from their ignorance. Ring laser gyroscopes -which are installed in some airplanes and ships- can easily detect and measure Earth’s rotation.
A ring laser gyroscope utilizes the Sagnac effect. Light travels at a constant speed, unaffected by the motion of the object emitting the light. Because of it, two light beams traveling in a loop, but to the opposite direction will complete the loop at a different time if the loop itself is rotating. Georges Sagnac discovered this Sagnac effect in 1913.
In 1925, the Michelson-Gale-Pearson experiment was the first to successfully measure Earth’s rotation using the Sagnac effect. At the time, Laser was not yet available, and they used a gigantic circuit measuring 603 m × 334 m.
In 1960, Laser was discovered. And in 1963, Macek & Davis demonstrated the first ring laser gyroscope. This technology vastly increased the precision, and instruments utilizing the Sagnac effect can be made much smaller. Today, ring laser gyroscopes are used in inertial navigation systems in many airplanes and ships.
Large scale ring laser gyroscopes -like several in the University of Canterbury, Christchurch, New Zealand- can even detect the tiny irregularities of Earth’s rotation, such as that caused by gravitational attraction from the Sun & the Moon.
Flat-Earthers did not know such instruments exist, and happy to claim there is no instrument sensitive enough to detect Earth’s rotation. In reality, directly measuring Earth’s rotation using the Sagnac effect was successfully accomplished by Michelson-Gale-Pearson almost a century ago.
A flat-Earth personality has even successfully measured Earth’s rotation using a ring laser gyroscope he acquired for $20000. Unfortunately, after he discovered it, he attempted to withhold the information because the result did not support his belief. The outcome was only known from the investigation by the documentary ‘Behind the Curve.’
www.eurekalert.org/pub_releases/2011-12/tum-fed122211.php
iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf
core.ac.uk/download/pdf/35460022.pdf
en.wikipedia.org/wiki/Ring_laser_gyroscope
en.wikipedia.org/wiki/Inertial_navigation_system
en.wikipedia.org/wiki/Sagnac_effect
#Gyrocompass
A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. The use of a gyrocompass is one of the seven fundamental ways to determine the heading of a vehicle. A gyroscope is an essential component of a gyrocompass, but they are different devices; a gyrocompass is built to use the effect of gyroscopic precession, which is a distinctive aspect of the general gyroscopic effect. Gyrocompasses are widely used for navigation on ships, because they have two significant advantages over magnetic compasses:
- they find true north as determined by the axis of the Earth's rotation, which is different from, and navigationally more useful than, magnetic north, and
- they are unaffected by ferromagnetic materials, such as in a ship's steel hull, which distort the magnetic field.
@@TheIsmaelIsaac gyrocompass
THE EARTH IS FLAT.
Garbage.
Your SHIFT key is stuck!
#Star Trail: Evidence the Earth is a Sphere
In the northern hemisphere, if we look at the sky to the north, we can observe stars rotate counter-clockwise around a point. This axis of rotation is not visible from observers in the southern hemisphere.
On the other hand, in the southern hemisphere, if we look at the sky to the south, we can observe stars rotate in the opposite direction. Conversely, this axis of rotation is not visible from observers in the northern hemisphere.
This motion of the stars cannot possibly happen in a flat-Earth.
#Stars in the Southern Sky Prove Earth is a Rotating Sphere
If we look toward the south at night in any location in the southern hemisphere, we will see the same set of stars. We will see the stars rotating around the south celestial pole, in the Octans constellation, near the star Sigma Octantis.
The flat-Earth model cannot explain the phenomenon. Looking at the so-called ‘flat-Earth map,’ we should see another set of stars on a different location in the southern hemisphere. The reason is that the flat-Earth model is a false representation of the Earth.
As an example, we will use five cities: Sydney (Australia), Papeete (Tahiti, French Polynesia), Santiago (Chile), Johannesburg (South Africa), and Jakarta (Indonesia).
If the Earth is flat, then observers on the different cities will face opposite each other, and therefore everyone should see different stars. However, in reality, they will see the same stars, only with different orientations. This observation is only consistent with the spherical Earth model and cannot be explained with the flat Earth model.
The flat Earth model was initially designed for the northern markets without much regard for what is happening in the southern hemisphere. Back then, it is difficult for those living north of the Equator to observe the southern stars, and it was not easy for most of them to confirm that the flat Earth model is nonsense. However, we live in modern times and do not have such an excuse, especially for those already living in the southern hemisphere.
en.wikipedia.org/wiki/Celestial_pole
en.wikipedia.org/wiki/Category:Southern_constellations
#Polaris Altitude from Multiple Locations on Earth
The angle (or altitude) to Polaris approximately corresponds to the latitude of the observer. This fact is observed on every location on Earth where Polaris is visible.
By tracing the path to Polaris from multiple locations on the flat Earth model, the lines will not point to a consistent position of Polaris. The reason is that the Earth is a sphere and the flat Earth model does not represent reality.
The position of Polaris today is conveniently very close to the north celestial pole. And therefore, the altitude or the angle between horizon and Polaris can be used to determine the approximate observer’s latitude.
South of the equator, Polaris is not visible and obviously cannot be used for navigation. Polaris is below the horizon and obstructed by the Earth. It is necessary to locate the south celestial pole in the sky to determine the observer’s latitude. It is more difficult as there is no bright star nearby, unlike Polaris in the north.
Polaris itself is not always the north star. Due to the Earth’s axial precession, the position of the north celestial pole will shift. Twenty centuries ago, the north celestial pole was closer to Kochab than Polaris.
All the observed facts are only possible if the Earth is a sphere, and impossible to happen if the Earth were flat.
en.wikipedia.org/wiki/Celestial_navigation
#Celestial sphere
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
The celestial sphere is a conceptual tool used in spherical astronomy to specify the position of an object in the sky without consideration of its linear distance from the observer. The celestial equator divides the celestial sphere into northern and southern hemispheres.
#Celestial poles
The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively.
th-cam.com/video/39NwiYdAkSs/w-d-xo.html
th-cam.com/video/8w3n-s9i7WQ/w-d-xo.html
th-cam.com/video/BGD3lhDCgpY/w-d-xo.html
th-cam.com/video/4zRh-1lymOw/w-d-xo.html
th-cam.com/video/UNiNJC3UHIo/w-d-xo.html
th-cam.com/video/dpaDKH9LOsc/w-d-xo.html
th-cam.com/video/6EBnwseiFs4/w-d-xo.html
www.reddit.com/r/flatearth/comments/w4crom/south_celestial_pole_right_at_the_zenith_90/
#Nautical Almanac
A nautical almanac is a publication that describes the positions of stars to enable navigators to use celestial navigation to determine their position at sea. Because the positions of stars are not fixed, a nautical almanac needs to be continuously revised.
Flat-Earthers claim that the positions of stars are fixed, and they only circle the celestial pole. In reality, stars’ positions do change, and we can find the historical positions of various stars from old publications of a nautical almanac.
One of the most well-known nautical almanacs is published by the government of the United Kingdom. This nautical almanac was first published in 1767, and new revisions are published every year. From different revisions of this nautical almanac, we can see the shift of the stars’ positions.
We often see flat-Earthers claiming that Polaris always stays in the same position. From a nautical almanac, we can understand that contrary to what flat-Earthers claim, Polaris’ position does change over time. In 1834, the official British nautical almanac gave us that the declination of Polaris is 88°25’40”. However, in the 1923 edition, it is 88°53’35”, and in 2018, it became 89°20’31”.
The determination of a ship’s position from celestial navigation depends on the accuracy of stars’ position in the nautical almanac being used. Because we do not have a fundamental problem in celestial navigation, we can be sure that the positions of stars being reported in nautical almanacs are correct. And therefore, we can understand that the change in stars’ positions is indeed occurring.
flatearth.ws/wp-content/uploads/2021/01/nautical-almanac.jpg
archive.org/details/nauticalalmanac30offigoog
archive.org/details/in.ernet.dli.2015.90651
asa.hmnao.com/
You can’t get a right triangle on a curve 😂 😂😂😂
You can't do celestial navigation.
Kinda like someone who struggles with basic arithmetic commenting on calculus.
Go back and finish grade school.
A good thing that we don't use right angle triangles then.
Nice flat earth proof. The mental contractions you use to convince yourself to ignore your own cognitive dissonance are incredible.
well with zero evidence and zero understanding of how celestial navigation works we'll just have to ignore you until you grow up.
@@iveneverseensuchbehaviorin5367 clearly if our understanding of celestial navigation comes from this video with the fictious modeling of angles from curved adjacents then we would all be lost at sea
@@njappboyUntil you come up with an alternative to the sight reduction process as has been employed for the last two hundred years, we'll just go with a globe with a mean radius of 3440.1 nautical miles.
@@marcg1686 stick with pretending you live on a ball and watch those government agency's computer generated images.
"Sweet dreams are made of these...some of them wanted to be abused"
So you’re sailing and navigating on the ball of water, that’s spinning and flying through vacuum? 🤪🌏🤡 tell me about those curved angles and triangles on the ball of water 🤣. ..”earth is not flat and it rotates and everything”? - 🤪🌏🤪🌏
Navigation works precisely because we understand the Earth's shape, we know distances etc..
We make use of the knowledge of the correct figure of the Earth for the purposes of navigation. This is how our ancestors were able to travel to the other side of the world (and back to the original location) without the modern technology we have today.
The American Practical Navigator, first published in 1802, was billed as the "epitome of navigation" by its original author, Nathaniel Bowditch. The text has evolved with the advances in navigation practices since that first issue and continues to serve as a valuable reference for marine navigation in the modern day.
The publication describes in detail the principles and factors of navigation, including piloting, electronic navigation, celestial navigation, mathematics, safety, oceanography and meterology. It also contains various tables used in typical navigational calculations and solutions, including the formulas used to derive the tabular data.
msi.nga.mil/api/publications/download?key=16693975/SFH00000/Bowditch_Vol_1.pdf&type=view
msi.nga.mil/api/publications/download?key=16693975/SFH00000/Bowditch_Vol_2.pdf&type=view
Books of navigation (1847 to 1944) - www.survivorlibrary.com/index.php/8-category/102-library-navigation
th-cam.com/video/UV1V9-nnaAs/w-d-xo.html
#Star Trail: Evidence the Earth is a Sphere
In the northern hemisphere, if we look at the sky to the north, we can observe stars rotate counter-clockwise around a point. This axis of rotation is not visible from observers in the southern hemisphere.
On the other hand, in the southern hemisphere, if we look at the sky to the south, we can observe stars rotate in the opposite direction. Conversely, this axis of rotation is not visible from observers in the northern hemisphere.
This motion of the stars cannot possibly happen in a flat-Earth.
#Stars in the Southern Sky Prove Earth is a Rotating Sphere
If we look toward the south at night in any location in the southern hemisphere, we will see the same set of stars. We will see the stars rotating around the south celestial pole, in the Octans constellation, near the star Sigma Octantis.
The flat-Earth model cannot explain the phenomenon. Looking at the so-called ‘flat-Earth map,’ we should see another set of stars on a different location in the southern hemisphere. The reason is that the flat-Earth model is a false representation of the Earth.
As an example, we will use five cities: Sydney (Australia), Papeete (Tahiti, French Polynesia), Santiago (Chile), Johannesburg (South Africa), and Jakarta (Indonesia).
If the Earth is flat, then observers on the different cities will face opposite each other, and therefore everyone should see different stars. However, in reality, they will see the same stars, only with different orientations. This observation is only consistent with the spherical Earth model and cannot be explained with the flat Earth model.
The flat Earth model was initially designed for the northern markets without much regard for what is happening in the southern hemisphere. Back then, it is difficult for those living north of the Equator to observe the southern stars, and it was not easy for most of them to confirm that the flat Earth model is nonsense. However, we live in modern times and do not have such an excuse, especially for those already living in the southern hemisphere.
en.wikipedia.org/wiki/Celestial_pole
en.wikipedia.org/wiki/Category:Southern_constellations
#Polaris Altitude from Multiple Locations on Earth
The angle (or altitude) to Polaris approximately corresponds to the latitude of the observer. This fact is observed on every location on Earth where Polaris is visible.
By tracing the path to Polaris from multiple locations on the flat Earth model, the lines will not point to a consistent position of Polaris. The reason is that the Earth is a sphere and the flat Earth model does not represent reality.
The position of Polaris today is conveniently very close to the north celestial pole. And therefore, the altitude or the angle between horizon and Polaris can be used to determine the approximate observer’s latitude.
South of the equator, Polaris is not visible and obviously cannot be used for navigation. Polaris is below the horizon and obstructed by the Earth. It is necessary to locate the south celestial pole in the sky to determine the observer’s latitude. It is more difficult as there is no bright star nearby, unlike Polaris in the north.
Polaris itself is not always the north star. Due to the Earth’s axial precession, the position of the north celestial pole will shift. Twenty centuries ago, the north celestial pole was closer to Kochab than Polaris.
All the observed facts are only possible if the Earth is a sphere, and impossible to happen if the Earth were flat.
en.wikipedia.org/wiki/Celestial_navigation
#Celestial sphere
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
The celestial sphere is a conceptual tool used in spherical astronomy to specify the position of an object in the sky without consideration of its linear distance from the observer. The celestial equator divides the celestial sphere into northern and southern hemispheres.
#Celestial poles
The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively.
th-cam.com/video/39NwiYdAkSs/w-d-xo.html
th-cam.com/video/8w3n-s9i7WQ/w-d-xo.html
th-cam.com/video/BGD3lhDCgpY/w-d-xo.html
th-cam.com/video/4zRh-1lymOw/w-d-xo.html
th-cam.com/video/UNiNJC3UHIo/w-d-xo.html
th-cam.com/video/dpaDKH9LOsc/w-d-xo.html
th-cam.com/video/6EBnwseiFs4/w-d-xo.html
www.reddit.com/r/flatearth/comments/w4crom/south_celestial_pole_right_at_the_zenith_90/
#Nautical Almanac
A nautical almanac is a publication that describes the positions of stars to enable navigators to use celestial navigation to determine their position at sea. Because the positions of stars are not fixed, a nautical almanac needs to be continuously revised.
Flat-Earthers claim that the positions of stars are fixed, and they only circle the celestial pole. In reality, stars’ positions do change, and we can find the historical positions of various stars from old publications of a nautical almanac.
One of the most well-known nautical almanacs is published by the government of the United Kingdom. This nautical almanac was first published in 1767, and new revisions are published every year. From different revisions of this nautical almanac, we can see the shift of the stars’ positions.
We often see flat-Earthers claiming that Polaris always stays in the same position. From a nautical almanac, we can understand that contrary to what flat-Earthers claim, Polaris’ position does change over time. In 1834, the official British nautical almanac gave us that the declination of Polaris is 88°25’40”. However, in the 1923 edition, it is 88°53’35”, and in 2018, it became 89°20’31”.
The determination of a ship’s position from celestial navigation depends on the accuracy of stars’ position in the nautical almanac being used. Because we do not have a fundamental problem in celestial navigation, we can be sure that the positions of stars being reported in nautical almanacs are correct. And therefore, we can understand that the change in stars’ positions is indeed occurring.
flatearth.ws/wp-content/uploads/2021/01/nautical-almanac.jpg
archive.org/details/nauticalalmanac30offigoog
archive.org/details/in.ernet.dli.2015.90651
asa.hmnao.com/
Foucault’s Pendulum Proves Earth is Rotating Sphere
Foucault’s pendulum proves Earth’s rotation. In the Northern Hemisphere, the pendulum rotates clockwise. In the Southern Hemisphere, it rotates counterclockwise. The pendulum turns faster if it is closer to the pole. On the Equator, the pendulum does not rotate.
Flat-Earthers invented various excuses to discredit Foucault’s pendulum. In reality, anyone not near the Equator can easily repeat the experiment, and it will give the expected result.
The Foucault pendulum will rotate with an angular velocity of 360° × sin φ per day, where φ is the latitude of the pendulum’s location. It rotates clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. There is only one explanation for why Foucault’s pendulum behaves like that: the Earth is a rotating sphere.
#Foucault Gyroscope
In 1851, Léon Foucault used a pendulum to demonstrate the rotation of the Earth. Despite his success, he was not fully satisfied with the pendulum experiment because of the dependency on the sine of latitude, which the public found difficult to understand. He later designed a device which he named ‘gyroscope.’
A spinning gyroscope keeps a constant axis of rotation in space, so it should slowly rotate with respect to an observer attached to the rotating Earth. The challenge was technical; it would need to have minimal friction, and it has to be able to spin for a sufficient duration so that the precession due to Earth’s rotation can be observed.
Gustave Froment helped Foucault to build the device. Using a hand crank and four stages of gearing, the gyroscope can be launched with the initial speed of 12000 rpm, allowing the rotation to persist for 10 minutes. It was sufficient to observe the precession due to Earth’s rotation, using a microscope.
www.sciencedirect.com/science/article/pii/S1631070517301019#br0110
tobin.fr/foucault.html
www.prc68.com/I/Gyroscopes.html
#Ring Laser Gyroscopes are Sensitive Enough to Measure Earth’s Rotation
A ring laser gyroscope (RLG) is an instrument for measuring the change in orientation and rotational velocity. It is sensitive enough to measure Earth’s rotation easily.
Flat-Earthers claim that there is no instrument able to measure Earth’s rotation. Such claim arose from their ignorance. Ring laser gyroscopes -which are installed in some airplanes and ships- can easily detect and measure Earth’s rotation.
A ring laser gyroscope utilizes the Sagnac effect. Light travels at a constant speed, unaffected by the motion of the object emitting the light. Because of it, two light beams traveling in a loop, but to the opposite direction will complete the loop at a different time if the loop itself is rotating. Georges Sagnac discovered this Sagnac effect in 1913.
In 1925, the Michelson-Gale-Pearson experiment was the first to successfully measure Earth’s rotation using the Sagnac effect. At the time, Laser was not yet available, and they used a gigantic circuit measuring 603 m × 334 m.
In 1960, Laser was discovered. And in 1963, Macek & Davis demonstrated the first ring laser gyroscope. This technology vastly increased the precision, and instruments utilizing the Sagnac effect can be made much smaller. Today, ring laser gyroscopes are used in inertial navigation systems in many airplanes and ships.
Large scale ring laser gyroscopes -like several in the University of Canterbury, Christchurch, New Zealand- can even detect the tiny irregularities of Earth’s rotation, such as that caused by gravitational attraction from the Sun & the Moon.
Flat-Earthers did not know such instruments exist, and happy to claim there is no instrument sensitive enough to detect Earth’s rotation. In reality, directly measuring Earth’s rotation using the Sagnac effect was successfully accomplished by Michelson-Gale-Pearson almost a century ago.
A flat-Earth personality has even successfully measured Earth’s rotation using a ring laser gyroscope he acquired for $20000. Unfortunately, after he discovered it, he attempted to withhold the information because the result did not support his belief. The outcome was only known from the investigation by the documentary ‘Behind the Curve.’
www.eurekalert.org/pub_releases/2011-12/tum-fed122211.php
iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf
core.ac.uk/download/pdf/35460022.pdf
en.wikipedia.org/wiki/Ring_laser_gyroscope
en.wikipedia.org/wiki/Inertial_navigation_system
en.wikipedia.org/wiki/Sagnac_effect
#Gyrocompass
A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. The use of a gyrocompass is one of the seven fundamental ways to determine the heading of a vehicle. A gyroscope is an essential component of a gyrocompass, but they are different devices; a gyrocompass is built to use the effect of gyroscopic precession, which is a distinctive aspect of the general gyroscopic effect. Gyrocompasses are widely used for navigation on ships, because they have two significant advantages over magnetic compasses:
- they find true north as determined by the axis of the Earth's rotation, which is different from, and navigationally more useful than, magnetic north, and
- they are unaffected by ferromagnetic materials, such as in a ship's steel hull, which distort the magnetic field
Yeah…. what he said
- @@marsa7600
go find the edge then 😂
Great video. Unfortunately, telling us "the earth is not flat" after acknowledging that you have to assume the earth is flat to get an elevation angle to the celestial body lol. Why would you need to assume it's flat if it's not? How do you get a 90 degree angle at the GP to the zenith on a curved baseline? Right triangles cannot have curved baselines. You're spitting a ton of facts, except when you baselessly assert, after trapping yourself, that the earth is not flat while all the evidence YOU'RE giving us points to the contrary. Thanks for being an expert hostile witness for the people that know the earth is not a ball.
More than two years have passed since the flat earth community discovered the marine sextant.
Not one of you has demonstrated how to determine a line of position. Not one.
There is no FE coordinate system.
NO FE charts and maps.
No FE Nautical Almanac.
In fact, you clowns cannot even agree upon whether the night sky is a dome or if it is planar.
I guess geometry never happened at the schools you visited.🤡
_''after acknowledging that you have to assume the earth is flat to get an elevation angle to the celestial body''_
Hey Russ, nowhere do we assume earth is flat to get an elevation angle
_How do you get a 90 degree angle at the GP to the zenith on a curved baseline?''_
No such thing in celestial navigation.
_''Right triangles cannot have curved baselines''_
Right triangles with curved baselines are not used when taking sextant sights.
You don't understand a single thing about celestial navigation. Go back to your papa flurf and tell him that he lied to you.
@@robertlafleur5179 “nuh uh” is not a refutation. Your response is one big “nuh uh.”
@@robertlafleur5179 “right triangles with curved baselines are not used when taking sextant sights” oh really? 8:22 must be awkward to watch. You gonna just keep lying?
@@russbonanno3765 Thanks for proving that you don’t understand anything about celestial navigation.
It's Flat! and the sailors/navigators did that according to Flat reality!!!!
You're living on a globe. We've checked.
Hahahaha “let’s imagine that the earth is flat” The earth has to be flat to do celestial navigation. There are no right triangles on a sphere. This guy uses techniques as if the earth were flat because it f***ing is. A spherical right angle triangle is a contradiction in terms. This guy only treats the earth as if it is flat when navigating with the stars. He keeps having to beat it into everyone’s head that the earth is round because celestial navigation requires a horizontal plane of reference. It is laughable.
Hey Willy, you think Earth is flat. Prove it. Solve this celestial navigation problem using flat earth only. Should be easy. No flat earther will touch it, they all run away, deflect or give excuses.
What will you do?
Here are 2 real Sun sights. Find the observer's position.
1st Sun sight:
February, 20 2010
17:26:26 UTC (GMT)
Sextant: 40°18.2' Artificial horizon
Sextant error: 0.0'
Upper limb of the Sun
2nd Sun sight:
February, 21 2010
00:16:02 UTC (GMT)
Sextant: 24°04.4' Artificial horizon
Sextant error: 0.0'
Lower limb of the Sun
No cheating now, you can't use globe science, only ''flat earth science''.
Show all your calculations.
Oh btw there is no spherical right angle triangle when we take a sextant sight, in fact there is not even any kind of triangle in a sextant sight. The line of sight from the observer to the star is parallel to the line from the GP to the star so there is no triangle. There is only an angle between the horizon and the star.
A spherical triangle exists in Celestial Navigation but it's a triangle on the surface of the globe as shown starting at 42:48.
He beats it that Earth is a globe only for flat earthers that haven't figured yet that Earth is not flat, normal people already know that Earth is a globe.
So when can I expect your flat Earth Celestial Navigation demonstration?
Nothing? I'll take it as it's imposssible to do flat earth celestial navigation.
Given your beliefs it's clear that you have the mind of a gold fish.
Skip to 54:00 and try to identify the 'spherical right angle triangle'.
Dunce.
" It is laughable."
Yep it certainly was.
You ran as far as you could.
Zero attempt to make your point.
(but truth be told you held a losing hand).