For a star, its initial mass is everything. It determines how quickly it burns through its hydrogen and how it will evolve once it starts fusing heavier elements. It's so well understood that ...

The Sun's transition from the main sequence to the red giant phase is a gradual process, spanning approximately a billion years. This transition begins with a subgiant phase where core hydrogen fusion ...

The Sun is mostly hydrogen and helium. Its core temperature is 27 million degrees Fahrenheit. The Sun is about 4.6 billion years old. It's a G-type main-sequence star. Key takeaways sponsored by The ...