What is this doing in the sky?

Just as I lay down on a picnic bench this appeared above me. I don’t think I have ever seen a rainbow stuck up in the sky like that. We walked about 15 km and I came to the albuerge about an hour before my companions. I can’t walk slowly because I have to much energy…and anxiety about getting a bunk! This is a lovely albergue with showers and a big airy room! The walk today was mostly through lovely farm land. I love this way of slowly traversing the landscape.