If you drag the letters written as earth, the earth rotates.
Then, on the upper right, you see the sky constellation seen from the viewpoint of the observer.
The constellations will only be visible at night.
When you drag the earth, the earth will orbit the orbital plane.
After the earth is spinning, rotate again to see what constellations are visible at night.
If you check Auto-rotate and rotate
It will rotate automatically while revolving.