Why Is Jupiter So Fat?

Imagine building a snowman. Usually, the closer you are to the pile of snow, the bigger your snowman gets because there is more material nearby. But Jupiter is far away from the Sun, where it should be smaller and colder with less stuff. Yet, Jupiter is huge! It has more than twice the mass of all other planets combined.

Scientists used to think Jupiter formed exactly where we see it today by sucking up everything around it. But if it stayed there, it would not have enough material to get so fat. Now, most experts believe Jupiter started closer to the Sun and then moved outward, like a magnet dragging iron filings along with it.

Think of a vacuum cleaner. As it moves across a rug, it picks up dust from different spots. Jupiter likely grabbed extra mass while traveling through the early solar system. This movement explains why it is so heavy despite its lonely location. It did not just stay put and eat; it went on a diet that ended with a massive feast.