Number One of Summer Days.
It's a bright star during the summer, rising and setting with the moon from the east to the west, tracing a bizarre path across the sky. During the warm season, it appears in the east, and during the ice age, in the west. Such chaotic movement reveals its extraordinary identity.
Only a planet can have such a strange astronomical trajectory.
After all, most of the stars in the sky are distant suns from the cosmos, almost stationary relative to the Dragon Sleep Continent solar system.
Therefore, no matter when one observes, the positions of the stars are basically fixed.
Only planets are constantly changing positions relative to the Dragon Sleep Continent, but through calculation, one can roughly predict their orbit in the short term.
A month earlier, Sullivan had led his team to predict the trajectory of Number One of Summer Days.