Long ago, on the west bank of the Milky Way, there lived a beautiful girl Orihime (Vega). She was a skilled weaver and worked very hard every day. Tentei, the Emperor of the sky was very happy with her diligence and married her to a very hard working cowboy Kengyu (Altair) from across the Milky Way. Kengyu and Orihime fell in love and started to live happily on the east bank. However, they spent all day long having fun together and forgot about their work. Tentei got very angry and took Orihime back to the west bank. Orihime was so sad that she cried for days and nights. Tentei felt sorry for her and allowed her to see Kengyu once a year. On the 7th of July, Orihime goes across the Milky Way to see her beloved husband Kengyu.
Story and more info here and here.
So why did I appropriate this festival name as my online moniker...
well, H and I got married 6 years ago today!