Here's the order of brightness of Jupiter's moons from Jupiter, from brightest to dimmest:

1. Io: The closest of Jupiter's four largest moons, Io is incredibly volcanic and reflects a lot of sunlight.

2. Europa: This moon is covered in a smooth, icy shell, making it relatively bright.

3. Ganymede: The largest moon in our solar system, Ganymede has a mix of dark and light areas, making it slightly dimmer than Europa.

4. Callisto: This moon is heavily cratered and dark, making it the dimmest of the four Galilean moons.

Note: While these are the brightest four moons, there are many other smaller moons orbiting Jupiter that are much fainter and more difficult to see.