The Sun will likely stop being a main-sequence star in:

Question

Quizplus · Accepted Answer

Our Sun is currently a main-sequence star, which means it is fusing hydrogen into helium in its core. This process has been ongoing for about 4.6 billion years, and is expected to continue for another 5 billion years. At that point, the Sun will have exhausted its hydrogen fuel and will start fusing helium in its core. This will cause it to expand into a red giant, ultimately engulfing the inner planets including Earth. Therefore, the correct choice is E - 5 billion years.

The Sun Will Likely Stop Being a Main-Sequence Star In