Why were red giants named so?

1 Answer
Nov 24, 2015

Because the star shines red and it is a giant due to expansion from original size.

Explanation:

As the star expands, it cools. Cooler stars shine red. It expands because when hydrogen fuses it becomes helium, the core becomes to shrink and the energy released by the heating of the helium core causes the outer hydrogen shell to expand greatly.