Does Fabric Really Fade in the Sun?

Before one year of sun exposure

This is a little birdie pincushion I made from recycled wool at Sew Biz Quilt Camp last summer. He's been sitting in the window of my sewing cottage for almost a year now. From inside, he looks just fine.

After one year of sun exposure

But the side that's been in the sun looks like this:


Even the rick-rack trim faded! Not to mention the vintage thread spool he's mounted on...

So, why does fabric fade in the sun?

Here are some interesting links:

Teachers answer a student's question at NEWTON.

AnswerBag.com explains how the moisture in fabrics reacts with the atmosphere to create a bleaching effect.

WikiHow shows how to use the process to your advantage with a technique for fading t-shirts to give them a vintage look!

I believe now from first-hand experience that the folks who are advising us to keep our quilts out of the direct sunlight know what they're talking about!