Bubbles, Bubbles, Everywhere

Narrator (Megan Watzke, CXC): For many kids (and those of us who are still kids at heart), bubbles are a lot of fun. We see bubbles blown out of soapy wands and others that float from the bottom of a fizzy drink to the top. But bubbles also represent important physical phenomena that can be found across many scales and in many different types of objects.

Let's look first at the soap bubble. Soap bubbles are formed when someone injects breath or air into a film of soapy water. This fits in with the definition of a bubble being a sphere enclosing liquid or gas. We can also find bubbles in space, where they are not made of soap like those here on Earth. Rather cosmic bubbles are blown out of the material we find in between stars and galaxies. Take, for example, this object. Its formal astronomical name is NGC 7635, but astronomers have nicknamed it the "Bubble Nebula." And it’s easy to see why when you look at it. The bubble in the Bubble Nebula is being blown up by a massive star that sits in its center. This star has powerful winds that are driven off of its surface, pushing the gas and dust that surround the star outward. The Bubble Nebula is much bigger than any soap bubble you will find on Earth. It stretches across over 63 trillion miles in diameter.

Even bigger still are the bubbles that astronomers find carved out in galaxy clusters. Galaxy clusters are the largest structures in the Universe held together by gravity. In addition to the hundreds or even thousands of individual galaxies that make up these gigantic objects, enormous amounts of hot gas envelope galaxy clusters. By using X-ray telescopes like Chandra, astronomers can examine this superheated gas. In objects like the galaxy cluster called MS0735.6+7421, they find that enormous bubbles spanning over seven times the size of the entire Milky Way galaxy have been formed in the hot gas. What could blow up such an enormous bubble? The answer is a supermassive black hole, weighing nearly a billion times the mass of the Sun, that lies at the center of the cluster. This black hole is shooting out powerful jets that push the 50-million-degree hot gas outward and create these incredible bubbles.

So the next time you pick up a bottle of bubbles, you may want to take a moment to realize how far-reaching bubbles truly are. You might only be able to inflate a bubble the size of a few inches, but elsewhere in the Universe, bubbles are forming in places and in sizes that are almost impossible to imagine.