What Is a Star?

In the night sky, stars look like tiny diamonds fastened to the ceiling. They seem peaceful, timeless, and unchanging. In reality, stars are huge. They are scattered through vast distances in space. They’re not timeless but are always changing, and those changes can be violent.

Each star is a giant, fiery ball of gases. Our sun is a star. It is made mostly of hydrogen and helium gases. The sun is extremely hot. Huge columns of gas sometimes leap from the surface.

Our sun is so big that a million Earths could fit inside it. More than a hundred Earths could stretch side by side across it. Other stars look much smaller than our sun, but that is because they are much farther away from us than the sun is.

Hot streams of gas leap from the surface of the sun.