How did the peppered moth population change over time?

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit

How do light years astronomers to determine the ages of distant objects in space ?

Number and variety of living organisms; includes genetic, species, and ecological types.