The factory method should return a CelestialBody object. This object should be able to do the following things:

print$($my$\_$planet.name$)$ will return Earth

print$($my$\_$planet.distance$)$ will return $149600000$

print$($my$\_$planet.diameter$)$ will return $12756\mathrm{.}3$

print$($my$\_$planet.moons$)$ will return $1$