How many things can you see in the night sky? A lot! On a clear night you can see the moon, some planets, and thousands of sparking stars. You can see even more with a telescope. You might see that many stars look larger than others. You might see that some stars that look white are really red or blue. With bigger and bigger telescopes you can see more and more objects in the sky. And you can see those objects in more and more detail. But scientists believe there are some things in the sky that we will never see. We won't see them with the biggest telescope in the world, on the clearest night of the year.That's because they're _ . They're the mysterious dead stars called black holes. You might find it hard to imagine that stars die. After all, our sun is a star. Year after year we see it up in the sky, burning brightly and giving us heat and light. The Sun certainly doesn't seem to be getting old or weak. But stars do burn out and die after billions of years. As a star's gases burn, they give off light and heat. But when the gases run out, the star stops burning and begins to die. So next time you look up at the night sky, remember: there's more in the sky than we can see! When a star's gases  _  ,the star begins to die.
burn run out give off heat get weak