Everything we have learned about stars comes from studying their A. distance
B. color
C. age
D. emission spectra

Which continents lie only in the northern hemisphere

Air masses are characterized by various properties including temperature humidity air pressure and wind speed. which of the following air masses is associated with low relative humidity and high air temperature ?

Which of the following is not a place where hydrogen can be found on earth? a. natural gas well b. atmosphere c. water d. mine