The observation of distant stars and galaxies is indeed a fascinating aspect of astronomy. While it is true that many galaxies are moving away from us, and in fact, the universe itself is expanding, there are several reasons why we can still see distant objects.
Light Travel Time: The speed of light is incredibly fast, but it still takes time to travel across vast cosmic distances. When we observe a distant star or galaxy, we are essentially seeing light that was emitted by that object in the past. The farther away an object is, the longer it takes for its light to reach us. So, even though the object may have moved since the light was emitted, we are still able to observe the light that was originally emitted.
Redshift: When objects in space are moving away from us, their light gets stretched, causing a phenomenon known as redshift. This means that the wavelengths of light from these objects become longer, shifting towards the red end of the spectrum. By studying the degree of redshift, astronomers can determine how fast an object is moving away from us and deduce its distance.
Expansion of the Universe: The universe itself is expanding, and this expansion happens at a large scale. It's important to note that this expansion does not involve objects moving through space like traditional motion. Instead, it's the stretching of space itself between objects. As space expands, it carries the light from distant objects along with it, allowing us to eventually observe it.
Hubble's Law: Edwin Hubble discovered that there is a relationship between the distance to a galaxy and the speed at which it is moving away from us. This relationship, known as Hubble's Law, allows astronomers to estimate the distance to galaxies based on their observed redshift.
By combining these factors and using various observational techniques and instruments, astronomers can study distant stars and galaxies, even if they are moving away from us. It is through these observations that we have gained significant insights into the nature of the universe, its expansion, and its evolution over time.