Use what you learned in this unit to describe at least one way in which each of earth's subsystems was altered during the precambrian era. research additional resources as needed.

Select the correct answer. what was edwin hubble's contribution to the field of astronomy? a. he discovered variable stars. b. he proved that the heliocentric model accurately described our solar system. c. he found a relationship between the period luminosity and distance of stars. d. he proved that the universe is finite. e. he discovered that the universe was expanding.