What term describes the apparent position change of a star as observed from Earth?

The term that describes the apparent position change of a star as observed from Earth is known as parallax. Parallax is the effect where an object appears to shift position against a distant background when viewed from different angles or positions. This phenomenon is commonly used in astronomy to measure the distances of nearby stars.

As Earth orbits the Sun, the position of nearby stars appears to change slightly against the background of more distant stars. This change can be measured, allowing astronomers to determine how far away those stars are. The concept relies on the geometry of the situation, where the baseline for measurement is the distance of Earth's orbit around the Sun.

Refraction refers to the bending of light as it passes through different media, which is not related to the change in apparent position of stars. Redshift describes the stretching of light waves from objects moving away from the observer, commonly used in determining the velocity of distant galaxies, and is also not applicable here. Declination is a celestial coordinate, similar to latitude on Earth, and it specifies a star's position in the sky but does not describe an apparent positional shift.

Therefore, the correct term to describe the apparent position change of a star, seen from Earth, is indeed parallax.