The exploration of Earth's interior is possible because _______________ produce vibrations called seismic waves.
Fill in the blank(s) with correct word
Question 2
Where are the Cepheid and RR Lyrae variable stars located on the H-R Diagram?
a. just above and to the right of B type stars
b. just above and to the right of O type stars
c. in the variable strip
d. in the instability strip
e. outside the H-R Diagram as missing items