The Sun appears spherical in shape because it is a massive ball of hot, glowing gases undergoing nuclear fusion at its core. Gravity compresses the gas and plasma within the Sun, causing it to form a nearly perfect sphere.
Gravity acts uniformly in all directions, pulling matter inward toward the center. As the mass of the Sun is evenly distributed, the gravitational force pulls the material toward the center, creating a spherical shape. The immense gravitational forces balance the internal pressure generated by the fusion reactions, maintaining the Sun's stability.
Furthermore, the Sun rotates on its axis, completing one rotation approximately every 24.5 Earth days at its equator and slightly longer at its poles. This rotation helps further shape the Sun into a spherical form due to the centrifugal force generated by the spinning motion.
When we observe the Sun from Earth, its spherical shape is visible because the Sun is a relatively close star, and its distance does not significantly distort its appearance. However, it's important to note that the Sun does exhibit some irregularities, such as sunspots, solar flares, and prominences, which can be seen on its surface.