Look at most child drawings, and you'll see the sun depicted as a yellow ball. Even many adults associate the color yellow with the star found at the center of the solar system. But the Sun isn't actually yellow; it's just an illusion caused by the Earth's atmosphere.
The powerful processes happening inside the Sun are so robust that it emits every color of light imaginable. Together, these colors form a pure white light, which is precisely what you'd see from space.
On Earth, however, the atmosphere filters much of the 'cool' light spectrum, leaving the 'warmer' colors visible to us instead. The filtered blue light refracts from atmospheric molecules, causing the blue appearance of our sky.
During times of sunrise and sunset, the colors of the Sun appear warmer than usual; this means orange or red instead of yellow. This is because of the angle of the Sunlight and the fact that it needs to pass through more atmospheric molecules to reach you.