In general, the surfaces of the planets will be ________ than the age of the solar system.
Fill in the blank(s) with correct word
Question 2
What is the source of Jupiter's excess energy?
A) Helium rain falling through its interior
B) The decay of radioactive elements in its dense core
C) Nuclear fusion in its hot, sunlike core of hydrogen
D) The slow escape of gravitational energy released during the planet's formation
E) The tidal stresses of the large Galilean moons
