Good question! We think that in about 5 billion years from now, the Sun will turn into a red giant. This happens when a star uses up the hydrogen at it’s core, which then contracts and gets extremely hot. In turn, this causes the outer layers of the star to expand out into space. The outer boundary of the Sun at this point will be deeper into the Solar System than the Earth currently stands, and so it will likely be swallowed up in the process.