Answer:
Galaxy, solar system, planet, moon
Step-by-step explanation:
The correct answer is above.
A Galaxy is essentially a collection of stars and other celestial bodies. Solar systems are component of galaxies because they form around stars (the sun is a star). The Milky Way, for example, has hundreds, potentially thousands of solar systems.
Planets are celestial bodies that go round a star in a solar or planetary system. The Milky Way has billions of planets.
Finally, a moon is a celestial body that goes round a planet, in other words, a satellite that has a large size. There are billions and billions of moons that accompany the billions of planets of the Milky Way.