In NASA’s Jet Propulsion Laboratory, scientists and engineers clap and cheer. They shake hands and hug. Words flash across a screen: “Welcome to Jupiter!” Their Juno spacecraft has arrived at the king of the planets—after traveling almost two billion miles! Driving a car two billion miles on Earth would take thousands of years. But Juno travels much faster than a car. Juno arrived after a five-year journey through space.

Juno carries nine instruments. These will be used to map the planet. Scientists also hope to answer other questions. How much water is in Jupiter’s atmosphere? Does Jupiter have a rocky core like Earth? Why does it have such bright northern and southern lights? What about Jupiter’s famous red storm? The storm has been swirling for hundreds of years. It makes a big red spot on the planet’s surface. How deep does the storm go? Why has it started shrinking?

Three wings stick out of the craft like blades on a windmill. These wings suck up sunlight. The sunlight powers the ship. No sun-powered spacecraft has ever gone as far as Juno. No people ride inside the craft. But three metal Lego people do. One Lego person has a big beard and holds a lightning bolt. He represents the made-up Roman god Jupiter. Another Lego person holds a magnifying glass. She represents Jupiter’s wife, Juno, searching for the truth. The third Lego person holds a telescope and a round planet. He represents Galileo Galilei, the real astronomer who discovered Jupiter in the 1600s.

It’s a good thing Juno’s passengers aren’t real! In 2018, Juno’s mission will end. The spacecraft will plunge into Jupiter and burn up. But before that, Juno will go around Jupiter 37 times. For scientists, the fun is just beginning!