17th Century Maritime Celestial Navigation

Many people wonder how ships made it across entire oceans without getting lost in the seventeenth century. Aaron continues his seventeenth century navigation series today by introducing us to celestial navigation.
Aaron started this series with an introduction to maritime piloting in the 17th century -- • Maritime Piloting in t...
Then followed with Maritime Dead Reckoning -- • Maritime Dead Reckonin...

[@noblereflex8332]

Great video! Really enjoying the content recently.

[@JYFMuseums]

Glad to hear it, that means a lot to us! Thanks

[@dmcd5635]

I've been wondering how they navigated back then and I finally looked it up, I'm glad I found your video.

[@JYFMuseums]

We're glad you found it too! be sure to check out our other navigation videos on piloting and dead reckoning as well.

[@blacktulip1064]

Thank you! Always interesting. 🧡

[@JYFMuseums]

Thank you, and you are so welcome!

[@snorribjorn5074]

Thank you for an interesting and informative video!

[@JYFMuseums]

Thank you!

[@erikrivas8256]

I understood the general concept of how early sailors navigated, but the specifics were always lost on me. Every video or text I've ever found on the topic thoroughly confused me. This video, however, is so simple and succinct. Thank you!

[@JYFMuseums]

You're welcome & thank you! We're glad that we made it easy to understand.

[@leoscheibelhut940]

Great presentation! JYF continues its excellence.

[@JYFMuseums]

Thank you!

[@richardglady3009]

Three hundred years in the future, I would learn piloting and celestial navigation at Naval OCS…it didn’t get any easier. Thanks for this video.

[@JYFMuseums]

You're welcome and Go Navy!

[@curtisbullock9739]

Super interesting and very well made!

[@JYFMuseums]

Thank you very much! We're glad you liked the video.

[@marklaurenzi1609]

Love this channel

[@JYFMuseums]

Thanks!

[@AJ-lh1si]

Very helpful video. So in Summer would I add the declination?

[@JYFMuseums]

Yes. North of the equator from March's Spring Equinox until September's Fall Equinox declination is added (spring and summer). From September's Fall Equinox until March's Spring Equinox declination is subtracted (autumn and winter).

[@okancanarslan3730]

nice documentary

[@JYFMuseums]

Thanks!

[@behorne89]

Great video!

[@JYFMuseums]

Thanks!

[@christianx8494]

The longitude problem could only be solved by exact timekeepers that made it possible to compare your observations (e.g. the moment a specific star becomes visible at the horizon) or reaches its highest angle above the horizon) to the data in nautical books and tablets issued by observatories on land. So, if your set of data tell you that sunrise at that specific day in winter would be at 7:25:47 Greenwich Mean Time at a given latitude and you observed that an hour and twenty minutes later you would know that you were 15 degrees (360 degrees divided by 24 hours make 15, plus another 5 degrees for those 20 minutes) , that make 20 degrees, to the west of the longitude of Greenwich. Astronomers wrecked their brains how to find a solution without an exact working machine- clock- that would show you the exact time of some distant place. Pendulum clocks are useless on rocking ships. And springloaded regulators in those days were not reliable enough. There are, though, two methods that required a lot of mathematics and exact observations, but they worked: There are two „clocks“ that we can see in the sky. They rotate against the background of the other celestial objects at even speed so that the changing angles between them and the stars and planets are the data that you need to work out where you are. It is the moon and the biggest four moons of Jupiter. Our moon travels around our planet within about 30 days. 360:30=12. That means the angle between the moon and some specific star changes by 12 degrees per day, that is half a degree per hour. If your nautical handbook, set of data, tell you that the angle between Sirius and the moon at a specific hour is 68 degrees at midnight at some given place and you measure 70 degrees at your midnight (local time) you must be four hours (60 degrees) away from that place. The moon method was good enough for mapping when your instruments could be fixed to some tripod that stood firmly on land. But on a rolling and rocking ship it lacked precision. The same thing is true for the Jupiter method. Here it is the rapidly changing image that the four tiny dots of the large Jupiter moons show you in a telescope.

[@MacXimus2009]

What did they do if it was overcast?

[@JYFMuseums]

Thanks for the question. The navigator needed to clearly see the celestial objects they were taking their measurements from -- the sun, moon or stars. If overcast, measurements could not be made and cloud cover could obscure celestial object for days.

[@christianx8494]

Before radio signals (DECCA and LORAN) ) and then later satellites (GPS ) were there, you could do nothing at all. Ships ran aground easily when foul weather caused them to drift away from their course and no „shooting the stares“ or the sun was possible to correct their faulty dead reckoning. It is the estuaries of rivers and entrances to sounds or the English Channel (from both sides) that are full of wrecks of ships that simply did not hit them in the right angle.

[@debbiej.2168]

I'm surprised that pullover jacket isn't longer. It's making me cold looking at his stomach only covered by his (probably, linen) shirt. Is there a reason for this? I would think sailors would want it to be quite a bit longer, so they'd be warmer.