During my family’s recent trip to the Japanese city of Hiroshima, we got caught up in one of the many festivals that dot the Japanese calendar.
Food stands, street musicians, dancers, and an unceasing river of celebrants clotted the streets — a teeming cacophony of joy.
I was surprised to learn that the next festival on the schedule was astronomically related. On the seventh day of the seventh month, the Japanese celebrate Tanabata, the Star Festival.
On that evening, people gather to look up at the stars and write their fondest wishes on small slips of paper called tankazu, which they then hang from a bamboo wishing tree.
The festival celebrates the steadfast love of the heavenly seamstress Princess Orihime and the “Star Boy” Hikobashi.
The Japanese apparently borrowed the story from the ancient Chinese myth about the Cowherd, the Weaver Girl, and the celestial river of light that we call the Milky Way today.
The Chinese myth has existed for thousands of years. The Japanese version of the story dates to at least the seventh century CE when the poet Hitomaro mentions it in one of his works. By the eighth century, the Japanese had borrowed heavily from Qixi, the Chinese festival celebrating the story, to create Tanabata.
The silvery river of light we call the Milky Way dominates the night during July and August. Our galaxy rises high in the sky and extends from the northeast to the southwest.
In ancient Chinese astronomy, the Milky Way was Tianhe, the deep Celestial River. The brightest part of the Celestial River is in the modern constellation Cygnus, the Swan.
The stars of Cygnus represent Tianjin, a place in the river that is exceptionally shallow and thus fordable at that point. Tianjin looks shallow there because a dark cloud of dust called the Great Rift obscures part of the Milky Way in that region.
In the Japanese version of the story, the kami, the spirits who live in the sky, value Princess Orihime because she creates beautiful clothing for them. To do so, she gathers pieces of fabric from the great river of light called the Milky Way.
Hikobashi is a simple but good-hearted tender of the sky cows. He lives on the other side of the Milky Way’s celestial stream from Orihime.
Orihime’s father introduces his daughter to the shy cowherd. The two innocents fall instantly and entirely in love and are married. Children soon follow.
The two lovers are utterly devoted to each other, perhaps too devoted. At length, members of the sky community notice the absence of the weaving maid. Her loom stands idle, and she had produced the sky’s most beautiful clothing.
Orihime’s father angrily puts the two lovers on opposite sides of the Milky Way to separate them forever.
The star we call Vega represents the weaving maid Orihime. In July and August, she sits above the Milky Way. Altair, the celestial cowherd Hikobashi, keeps his lonely vigil on the opposite side of the river of light.
Their children huddle close to their mother. We see them as the two dimmer stars in Lyra closest to Vega.
The grief of the lovers is so intense that even Orihime’s stern father shows compassion. He declares that they may briefly reunite once each year, on the seventh night of the seventh month of the Japanese lunar calendar.
On that night in August, if the skies are clear, a flock of black birds fly up to the heavens. They build a bridge of their wings to allow the lovers to cross the Milky Way.
As with many pronouncements by sky gods in many cultures, the father’s decree has a condition. If the sky is cloudy that night, Orihime and Hikobashi must wait and hope the Milky Way will shine brilliantly next year.
In ancient times, people did what they could to help them. For example, women wove garments to offer to the sky spirits to replace Orihime’s work.
When the Japanese switched to the Western solar calendar, the celebration of Tanabata slowly migrated to July 7, especially in urban areas. Sadly, the rainy season in Japan stretches from June to mid-July. The celestial paramours often must wait until the following year.
However, in some rural areas, the festival is still celebrated in August according to the dictates of the old lunar calendar. The weather is much better then, and the paramours are more frequently reunited.
Tom Burns is the former director of the Perkins Observatory in Delaware.
