Question

What is mean by cosmology?
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Answer 1

the science of the origin and development of the universe. Modern cosmology is dominated by the Big Bang theory, which brings together observational astronomy and particle physics.

Answer 2

Cosmology is a field of astronomy concerned with the origin and rest of the universe, from the Big Bang to the present day and beyond.

Explanation:

• "The scientific study of the large scale aspects of the universe as a whole," says the definition of cosmology.
• Cosmologists debate exotic notions such as string theory, dark matter, and dark energy, as well as whether there is only one universe or several universes (sometimes called the multiverse).
• While other branches of astronomy focus on single objects, events, or sets of objects, cosmology encompasses the entire cosmos from conception to death, with a variety of mysteries at each stage.
• The Sun is a star that revolves around Earth and the other planets, and every visible star in the sky is a sun in its own right.
• Some stars are brighter than the Sun, while others are fainter. Because the stars are all much farther away than the Sun, they emit far less light than the Sun. Because there are so many of stars, they seem densely packed in the Milky Way.
• The actual separations between stars are immense, to the point where their distances are commonly measured in units of how far light can travel in a given amount of time. In a vacuum, the speed of light is $3\times10^{10 }cm/sec$ (centimeters per second); at this rate, the Earth may be circled seven times in a single second.
• In terrestrial standards, the Sun, which is $500$ light-seconds from Earth, is a long way away; but, the next closest star, Proxima Centauri, is $270,000$ times farther distant at $4.3$ light-years$(4.1 \times10^{18} cm)$. The distance between the Sun and the stars on the opposite side of the Milky Way is on the order of $100,000$ light-years, which is the normal diameter of a massive spiral galaxy.