The North Star
« on: August 09, 2020, 08:55:01 PM »
Hello!

I was wondering about the North star. How come we cannot see it below the equator? Since we invented celestial navigation we have used it to find North right, so we know it doesn't move around? Why then, when we moved below the equator, did we have to resort to using the southern cross for navigation? How did the southern cross work for 100s of years if there is no south? 

Im sorry if this post came off as rude, I'm genuinely just confused

Best Regards

Offline edby

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Re: The North Star
« Reply #1 on: August 10, 2020, 05:29:30 PM »
Hello!

I was wondering about the North star. How come we cannot see it below the equator? Since we invented celestial navigation we have used it to find North right, so we know it doesn't move around? Why then, when we moved below the equator, did we have to resort to using the southern cross for navigation? How did the southern cross work for 100s of years if there is no south? 

Im sorry if this post came off as rude, I'm genuinely just confused

Best Regards

There is some material on Polaris in the wiki here https://wiki.tfes.org/index.php?title=Special%3ASearch&search=polaris.

But the simple answer is that navigators prefer to use sun position for navigation, which works equally well in the North or the South.

Re: The North Star
« Reply #2 on: August 10, 2020, 06:54:54 PM »
That's fine during the day but you also need to navigate at night.  How do you navigate in the southern hemisphere at night when the Sun ain't visible and being south of the equator there is no Polaris?
« Last Edit: August 10, 2020, 09:29:08 PM by IronHorse »

Offline edby

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Re: The North Star
« Reply #3 on: August 10, 2020, 09:37:48 PM »
That's fine during the day but you also need to navigate at night.  How do you navigate in the southern hemisphere at night when the Sun ain't visible and being south of the equator there is no Polaris?
They had the method of dead reckoning, i.e. estimating their position by speed and direction, which was actually quite accurate, and in any case you can navigate by any bright star if you have the charts and a suitable instrument.

[EDIT] From Cook’s log  November 1st 1768

Quote
Wednesday, 2nd. A Steady breeze and fine pleasant weather. This Afternoon, by the mean of Several Azimuths and the Amplitude, found the Variation to be 0 degrees 34 minutes East, from which it appears that about the aforegoing Noon we have Crossed the Line of no Variation in the Latitude of 10 degrees 38 minutes South, and, according to the following Observations, in 32 degrees 0 minutes West longitude from Greenwich. At 5 hours 5 minutes 0 seconds Apparent time a.m. the longitude of the Ship and the Observation of the moon and the star Aldebaran was found to be 32 degrees 0 minutes 45 seconds; at 8 hours 17 minutes 0 seconds, per sun and moon, 32 degrees 25 minutes 0 seconds; and at 9 hours 0 minutes 16 seconds, 32 degrees 19 minutes 0 seconds.
http://gutenberg.net.au/ebooks/e00043.html#ch5
« Last Edit: August 10, 2020, 09:49:27 PM by edby »