Final answer:
The distant galaxy is receding from Earth due to the expansion of the universe, a phenomenon described by Hubble's Law. Redshift in the spectral lines of galaxies is used to measure the rate at which they recede. These recessional speeds can vary slightly due to local motions or interactions with neighboring galaxies.
Step-by-step explanation:
The topic of the distant galaxy receding from Earth falls under the study of astrophysics, specifically the idea of the expanding universe and Hubble's law. Hubble's law states that the speed at which a galaxy is moving away from us is directly proportional to its distance. This is observed as a redshift in the spectral lines of distant galaxies. The distant galaxy you've mentioned is receding from the earth at a relative speed, which can be calculated using the provided value and the relativistic Doppler equation.
At 20% of the speed of light, relativistic effects start to become important, thus one has to use the relativistic Doppler equation to compute the true recession rate. Notably, the recessional speed of a galaxy can vary slightly due to local motions or interactions with neighboring galaxies. Despite these local variations, an observer in any other galaxy would see the same pattern of expansion that we do, indicating that we are not at the center of this galaxy expansion phenomenon. This motion is due to the stretching of space itself, not due to the motion of the galaxy through the space.
Learn more about Expanding Universe