Final answer:
The Sumerian invention based on their knowledge of astronomy is the calendar, which helped farmers track seasonal activities.
Step-by-step explanation:
The Sumerian invention that was based on their knowledge of astronomy is The calendar. Early priests in Babylonia, Egypt, China, and other countries studied the movements of the Sun, moons, and planets to create calendars for tracking seasonal activities. This invention helped farmers know when to plow and sow ahead of rainy seasons and time other seasonal activities.