Do stars change position in the sky and one star that doesn't move in the sky?
It's a common misconception that the stars we see in the night sky are fixed in space. In reality, all of these stars are part of our own Milky Way galaxy and are constantly in motion. However, because of the vast distances between them, we can't easily observe their movements relative to one another. This is why the stars appear to be fixed in their positions when we look up at the night sky.
The stars are not fixed, but are constantly moving. If you factor out the daily arcing motion of the stars across the sky due to the earth's rotation, you end up with a pattern of stars that seems to never change. The stars appear to be unchanging, always in the same constellations. But over millions of years, the stars change their relative positions as they orbit around their galactic center. So, the Milky Way galaxy is an ever-changing place. The stars are stationary but seem to move in the sky. Each day the Earth travels further in its orbit, and a different part of the night sky is visible. The stars appear seasonally, so the pattern will remain the same but seem to move across the sky. Therefore, over the course of a month, the position of the stars at a given time will shift by roughly 30 degrees. Over 12 months, the position of the stars will shift by 360 degrees. Hence, we see the same group of stars at the same time each year. This motion is due to the Earth's rotation. As the spin of the Earth carries us eastward at almost one thousand miles per hour, we see stars rising in the East, passing overhead, and setting in the West. The Sun, Moon, and planets appear to move across the sky much like the stars. The stars appear to be attached to a giant celestial sphere, spinning about the celestial poles, and around us, once every 23 hours and 56 minutes. These apparent star tracks are in fact not due to the stars moving, but to the rotational motion of the Earth. As the Earth rotates with an axis that is pointed in the direction of the North Star, stars appear to move from east to west in the sky. Polaris is the star in the center of the star field; it shows essentially no movement. Earth's axis points almost directly to Polaris, so this star is observed to show the least movement. The other stars appear to trace arcs of movement because of Earth's spin on its axis. The North Star, also known as Polaris, appears to stay fixed in our northern sky. It marks the location of the sky's North Pole, or the north celestial pole, the point around which the whole northern sky full of stars turns.
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