Ersa (moon)

Imagine Earth has a best friend that follows it around – that's our Moon! Ersa is like that, but it's a tiny moon that follows a HUGE planet called Jupiter. Jupiter is so big, it's like a giant beach ball, and Ersa is like a tiny pebble rolling around it. Ersa is one of many little friends Jupiter has! It's a moon because it orbits a planet, not the Sun directly.

Ersa is super small, only about 3 kilometers (or 2 miles) across. That's like the length of about 30 school buses lined up! It zips around Jupiter really fast. It takes Ersa less than one Earth day to go all the way around its giant planet friend. That's faster than you can go to school and back!

Ersa is made of rock, just like the ground you walk on. It's not a big, shiny ball like our Moon. Because it's so small and dark, it's very hard to see. Scientists found Ersa using special telescopes that can see faint things far, far away. It's like finding a tiny ant in a giant playground!

Even though Ersa is small and far away, learning about it helps us understand how our solar system was made. It's like putting together puzzle pieces! Every little moon and planet tells a story about the beginning of everything. Scientists study these tiny moons to learn more about Jupiter and its other many, many moons.