The fission reactions.
in theory it is because it has food source (earth) light source(sun and other suns) and all the other elements cells contain
They are each a source of light like the Sun.
They are each a source of light like the Sun.
the photons travel outward from a light source in all directions.
The sun is the source of heat and light for plant-life.
The terms light source and illuminant have precise and different meanings. A light source is a physical emitter of radiation such as a candle, a tungsten bulb, and natural daylight. An illuminant is the specification for a potential light source. All light sources can be specified as an illuminant, but not all illuminants can be physically realized as a light source.
Some stars are bigger than our galaxy, so probably a star somewhere.
No, the Sun is not the only light source in the univrse. Every star is it's own light source, just as the sun is, but due to there distance they are not very effective. The Moon also creates a light source, because it reflects the light from the Sun back to earth. In the same way, if we where on the Moon, the Earth would be a light source, reflecting the light from the Sun at the moon.
The Andromeda Galaxy is the closest one to the sun. Our galaxy is the closest one of all.
There is no such galaxy, the nearest galaxy is over 2 million light-years away.
There is no 'primary light source', as in one object that provides most of the light. In this solar system, our sun provides the primary light source. Other stars provide most of the light for other areas of the galaxy. The source of the shininess is light reflecting off the atmospheres or gases surrounding the planet. Please note that you should restrict your posts to one question per post.
The Andromeda galaxy is approximately 220,000 light-years in diameter. It is the closest spiral galaxy to our Milky Way galaxy.