I seem to remember being told that if you look into a basin of water on the evening of the Qixi Festival (七夕节), you will see the reflection of star-crossed lovers Zhinü and Niulang meeting on the swallow bridge.
I’ve never been able to find any record of such a belief so I probably imagined it, but the love story of the cowherd and the weaver is one of the few Chinese myths I was told by my mother when I was a child.
The celebration is also called Qiqiao, the Double Seventh Festival, Chinese Valentine’s Day, the Night of Sevens, or the Magpie Festival. The reason for the number seven occurring in so many of the names (Qixi means seventh evening), is because the festival is on the seventh day of the seventh lunar month, the one day the lovers are allowed to meet.
Zhinü and Niulang’s relationship was frowned on because Niulang was just a lowly cowherd, whereas Zhinü was from heaven. When the Jade Emperor found out that the pair had fallen in love and got married, he sent Niulang packing and ordered Zhinü home. Undeterred, Niulang gave chase but was cock-blocked by the Queen Mother of the West who conjured up a silver river (the Milky Way) to keep the lovers apart. However, a flock of magpies took pity of them and formed a bridge over the river so that Niulang and Zhinü could meet. The Jade Emperor was so impressed by the couple’s love that he decided to let them meet once a year. (Living apart was probably the secret to their successful marriage, but Chinese couples, obviously less cynical than I am, choose to simply celebrate that crazy little thing called love on Qixi.)
The festival is celebrated as Tanabata in Japan as Tanabata; Chilseok in Korea; and Thất Tịch in Vietnam.
The natural phenomenon linked to this festival is the visibility of the summer triangle made up of the stars Altair (Niulang), Vega ( Zhinü) and Deneb (the bridge).