Around 9:00 a.m. on May 31, green clouds appeared in the east sky of Santiago. The picture shows the clouds over Cordillera de los Andes, viewed from Joint ALMA Office (JAO). The clouds are rimmed with the color of vivid pink, and staff members at JAO were stunned by its beautiful color (though it is somewhat blurred in the picture). Clouds like this are called iridescent cloudsEwhich were considered as an auspicious sign in the old days. In physics, this phenomenon is supposed to be caused by the sunlight diffracted by moisture in the cloud.