Phone & Sunglasses!

[Silvs]

I have a Sony Xperia mobile phone. I also have a pair of stylish aviator sunglasses.

Now, when wearing said sunglasses, and my phone is held in portrait mode I can see the screen perfectly.

The second I turn it to landscape I cannot see a thing! If I remove the sunglasses the screen is on like normal.

I cannot get my head around the science!!

Thoughts?

[Silvs]

I think they are polarised. What's the theory behind it when the screen is horizontal then?