How is a star big?

Answer 1

They're different sizes.

Simplistic. Supergiants, Giants, Dwarfs, Sub dwarfs, White dwarfs.

Supergiants are huge. Some of them are large enough that, if they replaced the sun in our solar system, Jupiter would be the innermost planet; the orbits of all the inner planets would be inside the star. The largest known is VY Canis Majoris which is about 2,100 times larger than our Sun [See Link] which would mean 9,261,000,000 Suns would fit inside.

White dwarfs, on the other hand, are only about the size of the Earth (though they're very dense; in many cases they have about the same mass as the sun).

Neutron stars are quite small: a few miles in radius. They're incredibly dense, since they manage to pack a mass up to around 2 times the mass of the sun in that tiny space.

See link for pictorial representation of various star sizes.

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Our Sun is a Star. Sun is much much bigger than Earth. All stars are like Suns in the sky. Most Stars are much much bigger than our Sun.

The Sun's diameter is 864,938 miles (1,391,980 km). This is almost 10 times larger than the planet Jupiter and about 109 times as big as the Earth. The volume of the Sun is 1,299,400 times bigger than the volume of the Earth; about 1,300,000 Earths could fit inside the Sun

In fact, if you think of the Sun as a Basketball, the Earth would only be the size of the head of a pin

See the related link for a better idea.

Answer 2

They're different sizes.

Simplistic. Supergiants, Giants, Dwarfs, Sub dwarfs, White dwarfs.

Supergiants are huge. Some of them are large enough that, if they replaced the sun in our solar system, Jupiter would be the innermost planet; the orbits of all the inner planets would be inside the star. The largest known is VY Canis Majoris which is about 2,100 times larger than our Sun [See Link] which would mean 9,261,000,000 Suns would fit inside.

White dwarfs, on the other hand, are only about the size of the Earth (though they're very dense; in many cases they have about the same mass as the sun).

Neutron stars are quite small: a few miles in radius. They're incredibly dense, since they manage to pack a mass up to around 2 times the mass of the sun in that tiny space.

See link for pictorial representation of various star sizes.

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Our Sun is a Star. Sun is much much bigger than Earth. All stars are like Suns in the sky. Most Stars are much much bigger than our Sun.

The Sun's diameter is 864,938 miles (1,391,980 km). This is almost 10 times larger than the planet Jupiter and about 109 times as big as the Earth. The volume of the Sun is 1,299,400 times bigger than the volume of the Earth; about 1,300,000 Earths could fit inside the Sun

In fact, if you think of the Sun as a Basketball, the Earth would only be the size of the head of a pin

See the related link for a better idea.