In each day, we can observe stars drift about 1° in their movement around the celestial pole. In a month, they will appear to have moved about 30° when observed at the same time in the night. And in a year, stars are back to their original positions precisely a year before. This annual stellar motion is the basis for the calendar system we are using.
Some flat-Earthers think we see the same star constellations every night. From this assumption, they would conclude the Earth is stationary. But their claim is demonstrably wrong.
It is not hard to prove it. We can simply observe the position of the stars, for example, on every first night of the month, in the same location, and at the same hour. Stars will appear move about 30° in a month.
This annual stellar motion is the basis for solar calendar system. This calendar uses the cycle of the Sun with respect to distant stars as the basis for determining the length of a year.
This motion of stars can be regarded as evidence of Earth’s orbit around the Sun, although it takes more than that one evidence in order to prove heliocentrism: the fact that the Earth is in motion around the Sun.