The sun's electromagnetic radiation is produced by

The electromagnetic radiation of the sun is produced by atomic reactions that occur inside the sun.

Explanation:

The sun produces a huge amount of electromagnetic radiation due to the nuclear fusion reaction in its nucleus, in which the hydrogen is converted to helium. The temperature at the core of the sun is about 13,600,000 Kelvin, and this heat is transferred to the next layer by thermal radiation. After that, the heat is brought to the surface of the sun by convection. From the surface, where the temperature is about 5,700 K, the energy of the sun travels through the space in the form of light radiation. Some of this light comes to Earth, and some of the energy is trapped by the atmosphere, heating the Earth.

3. dark matter

empty space could also be a simple vacuum