What is the most populous region of both the united states and canada

The earth's inner core reaches temperatures that are at times greater than 9000°f. what causes this layer to remain solid despite the high temperature?

On nights when we see the new moon phase, what side of the moon are we seeing?

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks