why constellations are different and rotates differently in the southern hemisphere?
In: Earth Science
We can chart stars’ positions on a globe by indicating which part of the Earth each star is directly above at a given time.
As the Earth rotates, each star effectively traces out a latitude line on the globe.
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**Why stars rotate differently in different places:**
They don’t. All of the stars are rotating exactly the same way as all of the other stars.
They’re not rotating around the north pole or the south pole (although it might look that way if you try to squish the globe into a flat sky map), they’re just rotating around the Earth’s axis.
(In reality, of course, they’re standing still while *we* rotate around the Earth’s axis.)
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**Why different stars are visible from different places:**
How high a star is above the horizon depends on how its current position on the globe compares to your own. If it’s at your position, it’ll be directly overhead. If it’s 90° from your position, it’ll be on the horizon. If it’s more than 90° from your position, it’ll be below the horizon and you won’t be able to see it unless you climb a sufficiently-tall ladder.
So what stars you can see (assuming you remain at ground level) will depend on what latitude you’re at:
* If you’re at 52°N latitude (e.g. London or Berlin), then stars below 38°S will never rise and stars above 38°N will never set.
* If you’re at 40°N latitude (e.g. New York or Beijing), then stars below 50°S will never rise and stars above 50°N will never set.
* If you’re at 34°S latitude (e.g. Buenos Aires or Sydney), then stars below 56°N will never rise and stars above 56°S will never set.
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