Final answer:
The Sun began as a large, diffuse cloud of gas and condensed to form the star we see today; it did not shrank in size but became denser and hotter as it collapsed under its own gravity.
Step-by-step explanation:
The Sun began as a large, diffuse cloud of gas and has not grown or shrank to its current size. Instead, as the cloud collapsed under its own gravity, it became denser and hotter in its center, eventually leading to the formation of the Sun and the solar system about 4.5 billion years ago. Initially, the Sun was cooler, emitting only about 70% of the energy it radiates today. Our solar system's formation was part of a continuous process of star formation that occurs as interstellar material collapses to give birth to new stars, an activity that is ongoing in our Galaxy.