1. Astronomy and planetary exploration reveal the solar system’s

structure, scale, and change over time. As a basis for understanding

this concept:

a. Students know how the differences and similarities among the sun, the

terrestrial planets, and the gas planets may have been established during the

formation of the solar system.

b. Students know evidence from Earth and moon rocks indicates that the solar

system was formed from a nebular cloud of dust and gas approximately

4.6 billion years ago.

c. Students know the evidence from geological studies of Earth and other

planets suggest that the early Earth was very different from Earth today.

d. Students know the evidence indicating that the planets are much closer to

Earth than the stars are.

e. Students know the Sun is a typical star and is powered by nuclear reactions,

primarily the fusion of hydrogen to form helium.

f. Students know the evidence for the dramatic effects that asteroid impacts

have had in shaping the surface of planets and their moons and in mass

extinctions of life on Earth.