What would cause a purple sky at the neck of the hour glass opening?
Perhaps not enough density of atmosphere to reduce the frequency of photon radiation down from violet to indigo to blue ?
"The sun was beating down slantingly, as if we were in a southern latitude,
instead of in the far Northland. It was swinging around, its orbit ever
visible and rising higher and higher each day, frequently mist covered, yet
always peering through the lacework of clouds like some fretful eye of fate,
guarding the mysterious Northland and jealously watching the pranks of man.
Far to our right the rays decking the prisms of icebergs were gorgeous.
Their reflections emitted flashes of garnet, of diamond, of sapphire. A
pyrotechnic panorama of countless colors and shapes, while below could be
seen the green-tinted sea, and above, the purple sky".