Altair is the twelfth bright star in the whole day, which is 0/67 light-years away from the earth. Vega is the brightest star in Lyra, ranking fifth in the night sky, about 25.04 light years away from the earth.

By measuring the included angle between Altair and Vega, someone calculated that the distance between them was about 16 light years by using cosine theorem. So the magpie bridge must be at least 16 light years old! 1 light-year is equivalent to 946073047258 1 km, which means that the cowherd and the weaver girl have to cross the length of 946073047258 1x 16 km to see each other! Nature needs about 3.4 billion magpies to build a distant magpie bridge for cowherd and weaver girl to meet.

The Traditional Customs of Valentine's Day in China;

1. Bridging the Magpie Bridge: It is said that Altair and Vega meet through the Milky Way on Tanabata night, and people will build a magpie bridge in the courtyard or park to simulate the scene where Altair and Vega meet. On this bridge, people can write down their wishes and blessings.

2. Weaving Qiaqiao: China Valentine's Day is also called Qiaqiao Festival, because women will pray for wisdom and skills on this day. Girls will prepare colored silk thread and weave various handicrafts, such as puzzles, bracelets and earrings.

3. Courtship: On this day, young people will go to the temple to pray for marriage, and burn incense and pray in front of the temple where Niu and Zhinv live. I will pray that my love will go well and I can find my ideal partner.

4. Meteor shower viewing: On the night of Tanabata, there is usually a meteor shower. People will go to the suburbs or places where there is not much light pollution to watch meteors in order to make wishes and pray.