Compare the amount of time a 20 solar mass star will stay on the main sequence to the length of time its iron core can exist.
What will be an ideal response?
Question 2
The youngest features visible with telescopes on the Moon are:
A) the volcanoes seen erupting in the highlands.
B) the craters sitting atop the mare.
C) the darkest regions of the mare.
D) the bright polar caps of new ice.
E) the scarps recently created by tectonic activity.