The speed of light is not infinite. Light takes time to travel from distant galaxies to our eyes here on Earth. If a galaxy is 1 billion light years away, it has taken 1 billion years for the light emitted by said galaxy to reach us here, so (obviously) we are seeing the light emitted 1 billion years ago. In a sense, we are seeing 1 billion years into the past at the light emitted by that galaxy.
Spring is a good season for observing distant galaxies because it offers clearer skies with less atmospheric turbulence compared to other seasons. This results in better visibility of faint objects, allowing astronomers to capture more detailed images of distant galaxies. Additionally, spring nights are longer and have darker skies, providing more observing time for studying these celestial objects.
en.wikipedia.org/wiki/Spectroscopy
Briefly, the Steady State theory assumes that the Universe looked the same in the past as it does now. Observations of distant galaxies showed that this is not the case - distant galaxies are quite different to the ones that are closer by. Note that if you look at distant galaxies, you are observing the past of the Universe, because of the time it takes light to get here. That evidence played a part, but it was the detection of the "cosmic microwave background radiation". That was what convinced most astronomers that the Big Bang Theory was correct.
Scientists study distant galaxies to understand the formation, evolution, and properties of galaxies over time. By observing galaxies that are far away, they can explore the universe at different epochs and gain insights into how galaxies have changed and evolved since the early universe. Studying distant galaxies also helps scientists refine theories about the laws of physics and the nature of the universe as a whole.
Astronomers can determine the expansion of the universe by observing the cosmic background radiation, and the red- or blue-shifting of distant objects.
Astronomers conclude that the universe is expanding, because wavelengths are increasing.
Because the universe as a whole is expanding, distant galaxies are moving away from us. As a result, electromagnetic waves emitted by those galaxies experience what is known as a red shift. Their wavelengths get longer.
An ultraviolet wavelength telescope can be used to study distant galaxies as ultraviolet light is emitted by hot, young stars and can provide information about star formation rates and the overall properties of the galaxies. By observing in the ultraviolet, astronomers can gain insights into the early stages of galaxy evolution and the presence of specific elements in the galaxies, contributing to a deeper understanding of the universe's history and dynamics.
Large telescopes are used to study distant galaxies because they can gather more light, allowing for better resolution and the ability to detect fainter objects. Their larger size also grants them a greater light-gathering capacity, which is essential for observing objects that are billions of light-years away. Additionally, large telescopes offer higher sensitivity and better data collection capabilities, enabling astronomers to analyze and study distant galaxies in greater detail.
The "nucleus".
shifted to longer wavelengths, indicating that the galaxies were moving away from us. This observation led to the development of the theory of the expanding universe.
It has allowed astronomers to find out more about the universe, creating clearer more detailed images, also allowing them to look further into the universe to see things such as distant galaxies, stars and planets.