Describe the movement of the Earth based upon the perceived change in positions of the stars
The perceived change in positions of stars is a result of the movement of the Earth. From our perspective on Earth, it appears as though the stars are moving across the sky throughout the night. However, in reality, it is the Earth that is rotating on its axis, giving us the illusion of stars moving.
The Earth completes one full rotation on its axis in approximately 24 hours, which we call a day. As the Earth rotates, different parts of its surface are exposed to the Sun, causing day and night. This rotation gives the impression that the stars are moving from east to west.
In addition to the rotation on its axis, the Earth also orbits around the Sun in a nearly circular path called an orbit. This journey takes approximately 365.25 days to complete, forming what we know as a year. The Earth's orbit is not perfectly circular but slightly elliptical, causing variations in distance from the Sun over the course of the year.
As we move in our orbit around the Sun, different constellations of stars become visible at different times of the year. This is because our position in space is changing, altering our perspective of the stars. For example, during summer in the northern hemisphere, we can see different stars than we can during winter.
By observing the perceived change in positions of stars over time, astronomers can study the Earth's motion and calculate things like the length of a day, the tilt of the Earth's axis, and the Earth's orbital period. These observations and calculations are the basis of our understanding of Earth's movement and its relationship to the stars.