1) Earth formed 4.5 billion years ago from a great cloud of dust and gas that collapsed to form the solar system. 2) All planets orbit in the same direction and plane, evidence they formed from the same disk surrounding the young sun. 3) The nebular hypothesis proposes the solar system formed as a giant cloud of dust and gas collapsed, with denser matter clumping together to form planets and planetesimals.

1. Earth and Other Planets Chapter 16 Great Idea: Earth, one of the planets that orbit the Sun, formed 4.5 billion years ago from a great cloud of dust.

3. The Formation of the Solar System

5. The Solar System

8. Mass in the Solar System

9. The Planets and Their Characteristics

11. The Stages in Solar System Formation

12. The Inner Planets – Small and Rocky

13. Jupiter – Gas Giant Planet

16. Artists Impression of the Earth’s Great Bombardment

17. Disk around a Young Star

19. The Principal Layers of the Earth

22. Formation of the Earth’s Moon

26. Exploring the Solar System

28. Surface of Mars

29. The Phoenix Lander on Mars

32. Theoretical View of the Interior of Jupiter

33. Comet Shoemaker-Levy Impacted Jupiter in 1994

34. Saturn with Its Rings and Moons

36. Artist’s Conception of the Oceans of Europa

38. Pluto and Its Moon, Charon

43. Comet’s Tail

45. Major Meteor Showers

47. Changes in Redshift or Blueshift of Light

48. Planet in Front of a Star

49. Kepler Satellite