One of the first breakthroughs in understanding the universe came with the realization that Earth is not at the center of the universe. In the 16th century, Nicolaus Copernicus proposed that the planets, including Earth, revolve around the Sun. This heliocentric model of the solar system challenged the previously held geocentric model, which placed Earth at the center.

In the 17th century, Galileo Galilei made significant contributions to our understanding of the universe. Using a telescope, Galileo observed the phases of Venus, the moons of Jupiter, and the rings of Saturn. These observations supported the heliocentric model and helped in the debunking of the traditional geocentric view.

In the early 20th century, Albert Einstein revolutionized our understanding of space and time with his theory of general relativity. This theory proposed that gravity is not a force but rather a curvature of space and time caused by the presence of matter and energy. General relativity successfully explained phenomena such as the bending of light around massive objects like stars.

The study of the universe continued to progress with the discovery of the expanding universe in the 1920s. Astronomer Edwin Hubble observed that distant galaxies appeared to be moving away from us, suggesting that the universe is constantly expanding. This insight led to the development of the Big Bang theory, which proposes that the universe began as a singularity and has been expanding ever since.

In the latter half of the 20th century, the field of astronomy witnessed rapid advancements due to the advent of space telescopes and other technological innovations. The Hubble Space Telescope, launched in 1990, has been invaluable in observing distant galaxies and expanding our knowledge of the universe.

Today, scientists continue to explore the mysteries of the universe through various methods, including the use of satellites, ground-based telescopes, and space probes. With ongoing missions such as the Mars rover, the search for extraterrestrial life, and the study of black holes, our understanding of the cosmos is ever-evolving.

Overall, the study of the universe has come a long way, from ancient civilizations' observations and beliefs to modern scientific discoveries and theories. As our technology and knowledge continue to advance, we can expect even more exciting breakthroughs and revelations about the nature of the universe.