From the Wikipedia:
Tanabata (七夕, tanabata?, meaning "Evening of the seventh") is a Japanese star festival, derived from the Chinese star festival, Qi Xi (七夕 "The Night of Sevens").
It celebrates the meeting of Orihime (Vega) and Hikoboshi (Altair). The Milky Way, a river made from stars that crosses the sky, separates these lovers, and they are allowed to meet only once a year on the seventh day of the seventh lunar month of the lunisolar calendar. The celebration is held at night, once the stars come out.
Large-scale Tanabata festivals are held in many places in Japan, mainly along shopping malls and streets, which are decorated with large, colorful streamers.
In our June 25th meeting, we'll be constructing a Tanabata tree and filling it with wishful ornaments. The Tanabata tree will then be displayed at the Reader's Den department for the public to add their wishes on the tree. Meeting will start at 3:45pm in room CL2 (second floor of the Central Library).
-Jason