The Moon's gravity is only _______________ that of Earth.
Fill in the blank(s) with correct word
Question 2
A nova is caused by the ignition of ____.
a. hydrogen fusion in material on the surface of a white dwarf
b. carbon fusion in a white dwarf core
c. helium fusion in the core of a massive red giant
d. silicon fusion in the core of a high mass star
e. iron fusion in the core of a high mass star