Question

Which is the brightest star in the night sky. Why is it so bright or what makes it bright?

Answer 1

Venus is one of the brightest objects in the night sky. Venus is so bright because its thick clouds reflect most of the sunlight that reaches it (about 70%) back into space, and because it is the closest planet to Earth. Venus can often be seen within a few hours after sunset or before sunrise as the brightest object in the sky (other than the moon). It looks like a very bright star. Venus is the brightest planet in the Solar System.
venus is not a star but a planet.it only reflects the sunlight.

stars produce light .sun itself is a star.