What is the difference between a main sequence star and a red giant star?

Stars go through different stages in their lifetime. Two such stages are main sequence and red giant. Main sequence stars are stars that have just started to fuse hydrogen atoms in their core. They are stable and shine bright. Red giant stars, on the other hand, are stars that have exhausted the hydrogen in their core and have started to fuse helium. They are much larger and brighter than main sequence stars, and have a reddish color due to their lower surface temperature.

Main sequence stars have a mass ranging from 0.08 to 50 times that of the sun. They are the most common type of star in the universe and are known for their stability. Red giant stars, on the other hand, have a mass ranging from 0.3 to 8 times that of the sun. They are much larger in size and can be up to 100 times brighter than the sun.

Another difference between main sequence and red giant stars is their lifespan. Main sequence stars can live for billions of years, while red giant stars have a much shorter lifespan of a few million years.