Describe the brightness and temperature of the stars classified as giants.

List four observations that indicate that a chemical reaction may be taking place

(1.6 × 10-19)(5.0 × 106) = c × 10d identify the missing numbers below to show the result of multiplying the numbers.

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. 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.