Stellar evolution
The outer layers of the star will get much, much bigger. The star will make much more light, sometimes as much as ten thousand times as much as it did at first. Since the surface of the star will get bigger, this energy will be spread out over a much larger area. Because of this, the temperature of the surface will go down and the color will change to red or orange. It will become a red giant. It can swallow up any planets that orbit around it.