Different stars visible from northern and southern hemispheres

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  • #1
PainterGuy
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It's a general question and not even sure if I should be posting it over here in section. Anyway, one cannot see Big Dipper from some countries in Southern Hemisphere, countries such as New Zealand and southern parts of Australia. People in Northern Hemisphere and Southern Hemisphere get to see different sets of stars. It is still true as it was in the past.

In the past, stars played an important role in sea navigation. If a European navigator wanted to travel to New Zealand in the past, wouldn't it affect his ability of navigation since he wouldn't have access to all of his regular navigations tools which are stars?

Also, what other way this different view of stars from Northern and Southern Hemispheres affected the people of those Hemispheres?

Thanks for the help, in advance!


Helpful link(s):
1: https://en.wikipedia.org/wiki/Celestial_navigation
 

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  • #2
Drakkith
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In the past, stars played an important role in sea navigation. If a European navigator wanted to travel to New Zealand in the past, wouldn't it affect his ability of navigation since he wouldn't have access to all of his regular navigations tools which are stars?
Somewhat. You can still find north even if you can't see the north star as long as you are familiar with the constellations. You just won't be able to use the north star for high-accuracy navigation.
 
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  • #3
tech99
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The best star for navigation is possibly the Sun, because it makes it easier to see the horizon, allowing latitude to be obtained at noon. With a chronometer we then have longitude at noon, Alternatively, by using observations a few hours apart, we can find position without making a noon observation.
In about 1890, Capt Slocum navigated round the World without an accurate chronometer (an old tin clock) by using additional observations of the Moon, a system known as Lunars. The navigational tables for this are no longer published.
Since 1926, Reeds Nautical Almanac has provided the geographical position of Sun, Moon and 60 navigational stars for every second of the year in just a slim publication.
 
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  • #4
sysprog
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For the sake of completeness, when I was a kid, I sought (without success) to procure a 60°S corollary of this classic 60°N (I think) device (I had the original Edmund brand (I nabbed a pic of it from ebay where it can be had for under $15 including shipping)):

1645774385649.png


This is the latest version:

1645772921248.png


When I saw this, I was dismayed that the Southern Cross was not visible (I was then (as now) in Chicago area, about 41°N latitude, so I couldn't see that set of stars anyway).
 
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  • #5
snorkack
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The best star for navigation is possibly the Sun, because it makes it easier to see the horizon, allowing latitude to be obtained at noon.
Which requires opportunity to make observation at noon, and then measuring a large angle.
In contrast, observing stars passing zenith at night can be done any time at night. If horizon is hard to see in the dark, how easy is it to spot exact zenith (direction of gravity)? Anyway, sky is full of latitude markers. Like Alkaid - the southernmost star of Big Dipper (at the end) marking 49 North and thus if it passes zenith on Atlantic, you are on your way to mouth of English Channel and landfall in Normandy.
 
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  • #6
anorlunda
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Latitude is much easier to observe than longitude. If no chronometer was onboard, they could use the method still taught to modern sailors as "emergency navigation". Namely, Unless you are in the Southern Ocean, sailing East or West is guaranteed to bring you to land. I kept a laminated card in my life raft with emergency navigation tips. Emergencies aside, the point is that latitude is the important one.

There is also a very entertaining book entitled Longitude.

As time passed and no method proved successful, the search for a solution to the longitude problem assumed legendary proportions, on a par with discovering the Fountain of Youth, the secret of perpetual motion, or the formula for transforming lead into gold. The governments of the great maritime nations--including Spain, the Netherlands, and certain city-states of Italy--periodically roiled the fervor by offering jackpot purses for a workable method. The British Parliament, in its famed Longitude Act of1714, set the highest bounty of all, naming a prize equal to a king's ransom (several million dollars in today's currency) for a "Practicable and Useful" means of determining longitude.
 
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  • #7
Ibix
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And then Harrison invented his "practicable and useful" clock and sent it to the Longitude Board who adopted it and then stopped answering their mail in the matter of the reward, as I recall. :rolleyes:
 
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  • #8
phyzguy
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Also, what other way this different view of stars from Northern and Southern Hemispheres affected the people of those Hemispheres?
As an astronomer, one of the ways this affects us is that we need to build telescopes in both hemispheres. A good example are the Gemini telescopes, twin 8 meter telescopes, one in Hawaii, and one in Chile.
 
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  • #9
collinsmark
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It's a general question and not even sure if I should be posting it over here in section. Anyway, one cannot see Big Dipper from some countries in Southern Hemisphere, countries such as New Zealand and southern parts of Australia. People in Northern Hemisphere and Southern Hemisphere get to see different sets of stars. It is still true as it was in the past.

Yes, but it's not a completely different set of stars. There's lots of overlap. And for any practical situation (e.g., sailing along in a sailboat), there's always lots and lots of overlap.

For example, no matter where you are in the world* you'll be able to see at least a little bit of the zodiacal constellations near the celestial equator.

*(If you're in the antarctic or arctic latitudes in your hemisphere's summertime, it will be difficult to see any stars at all. So yes, I'm ignoring extreme latitudes here.)

In the past, stars played an important role in sea navigation. If a European navigator wanted to travel to New Zealand in the past, wouldn't it affect his ability of navigation since he wouldn't have access to all of his regular navigations tools which are stars?

He would need to gradually update his star charts as he sailed further south. But once he has more comprehensive star charts, he would use his tools in the same basic way he did in the Northern hemisphere.

It's not like when you cross the equator, BAM! the skies are completely different. It's very gradual. If you were to walk a mile south from your home, the night sky would be ever-so-slightly different than it looked like at home. Walk another mile south and it would look ever-so-slightly different still. Nothing would change suddenly. It's all very gradual.

Also, what other way this different view of stars from Northern and Southern Hemispheres affected the people of those Hemispheres?

Different sites to see, I suppose.
 
  • #10
snorkack
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He would need to gradually update his star charts as he sailed further south. But once he has more comprehensive star charts, he would use his tools in the same basic way he did in the Northern hemisphere.

It's not like when you cross the equator, BAM! the skies are completely different. It's very gradual. If you were to walk a mile south from your home, the night sky would be ever-so-slightly different than it looked like at home. Walk another mile south and it would look ever-so-slightly different still. Nothing would change suddenly. It's all very gradual.
Also he would need to update his map, anyway. Make a trip south, and you can see basically the whole southern sky in a single clear night. But what is the use of knowing you are at 40 South unless you know which lands exist on that latitude - how far south do South Africa, West Australia, Tasmania, New Zealand and South America extend?
 

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