Tenshô. In traditional charts for renku, this category includes astrological phenomena other than the moon, the latter being a special category for deep historical and cultural reasons, the foremost being its association with the harvest. Every type of renku longer than the two-verse tan renga requires a certain number of moon verses. But you should also feel free to touch on other celestial objects and phenomena: stars, planets, comets, meteors, and the like. Because celestial bodies are dazzling and memorable, the rule is to not have them appear back-to-back. It is recommended to separate them by at least two intervening verses.