2. the celestial bodies stars

3. planets

4. moons

11. what’s the number of moons rotating around planets ?

12. mercury any moon rotate arounnd it

13. venus any moons rotate around it

14. earth one moon rotates around it

15. mars two moons rotate around it

16. jupiter 62 moons rotate arount it

17. saturn 60 moon rotate around it

18. uranus 27 moons rotate around it

19. neptune 12 moons rotate around it

27. inner planets group

28. the outer planets

31. the difference of gravity force on the surface

34. so the planets revolve around the sun in the fixed orbits by the action of the sun’s gravitional force on them

35. arrange the planets descending regarding the acceleration due to the gravity mentioned in following table :

36. jupiter 22.88

37. neptune 11.00

38. earth 9.78

39. saturn 9.05

40. venus 8.60

41. uranus 7.77

42. mercury 3.78

43. mars 3.72

45. refracting telescope

46. reflecting telescope