Ancient rocks hide deep in the ground near a volcano. The rocks are getting hotter . . . and hotter . . . and hotter. Then, pop! The helium leaks out of them! The helium travels up. But it doesn’t make it all the way into the open air. It gets caught under the ground. This lighter-than-air gas used to fill party balloons has many important uses. But for years, scientists thought the world was running out of it. Now they know better. Here, in Tanzania, Africa, they have found enough helium underground to satisfy the world’s helium needs for six or seven years!

Until now, people have discovered most of our helium by accident while drilling for oil or gas. But when helium became scarce, they tried something new. They looked for helium on purpose. They knew helium comes from underground rocks. They also knew those rocks have to get very hot in order to let the helium out. So they did more studying. Their research gave them a new idea: Look near a volcano! They found volcanic activity in the East African Rift Valley. Near the activity, they found gas fields. A gas field is land with valuable gasses below its surface. In the gas fields, they found helium—lots of it.

Experts guess the fields hold 54 billion cubic feet of helium. What could you do with that much helium? If you wanted to, you could operate 1.2 million MRI machines (tools used in medicine to create images of a person’s insides). Or you could make everyone on Earth have a squeaky voice for about 20 minutes! (The second one would be fun. But the first one would be very useful. It would probably save people’s lives.)

Researchers aren’t done. They will likely go looking for more helium in another part of the world. Even Tanzania’s helium won’t last forever.