If you're north of the equator but south of a latitude of about 25 degrees, which is around say Hawaii and parts of northern Africa, you can still see the Southern Cross.
So why can't you see the Southern Cross any further north, or all year round for that matter?
The curvature of the Earth gets in the way.
In fact it was by watching the constellations move across the sky as the ancient Greeks travelled across the Earth, that they came to realise that the Earth was spherical and not flat
http:// www.abc.net.au/science/articles/2010/06/17/2929420.htm
Bye!