A star is a luminous spheroid of plasma held together by self-gravity. [1] The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light.
A star is any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources. Of the tens of billions of trillions of stars in the observable universe, only a very small percentage are visible to the naked eye.
These large, swelling stars are known as red giants. But there are different ways a star’s life can end, and its fate depends on how massive the star is.
If you have read How the Sun Works, you already know a lot about the nature of Earth's nearest star. As you read the following pages, you'll find out even more about what you can see in the night sky.