Free-form --

Send your two partners each a minimum of one photo of the sky and anything you see in it - planes, stars, sun, moon, clouds

-- sender's choice of presentation, but, if mailing as postcard, PLEASE protect your nice photo with good card stock backing and even consider lamination

-- also, if mailing as a postcard, to meet mailing requirements, must me minimum size of 3.5" by 5" (or metric equivalent)

-- professionally printed OR your own home printer, if excellent quality and will do your photo justice

-- past photos you've taken okay, as long as you were the photographer