How does the universe's expansion affect the observation of distant galaxies?

The universe's expansion causes distant galaxies to appear to be moving away from us.

As the universe expands, the space between galaxies also expands. This means that the light from distant galaxies has to travel through more space to reach us, causing it to be stretched out and shifted towards the red end of the spectrum. This is known as redshift and is a key indicator of the universe's expansion. The greater the distance of the galaxy, the greater the redshift.

The redshift can be used to calculate the distance of the galaxy from us, as well as its velocity. This information can then be used to map the distribution of galaxies in the universe and to study the large-scale structure of the universe.

However, the redshift also means that the light from distant galaxies is fainter than it would be if the universe were not expanding. This is because the light is spread out over a larger area as it travels through space. This can make it difficult to observe and study distant galaxies, particularly those at the edge of the observable universe.

Despite these challenges, observations of distant galaxies have provided valuable insights into the early universe and the processes that have shaped its evolution. The expansion of the universe continues to be a key area of research in astronomy and astrophysics.