Question

How does light affect the universe?

Answer 1

Light from the night sky enlivens our universe.

Explanation:

Light does not affect but enlivens our universe.

Trillions of stars in flame are sources of light.

I do not think that the reflected sunlight from Luna,, during

Full-Moon night, affects us.

In fact, it evokes tranquility, after direct daytime radiation..

Radiation might be good or harmful. But light is good for our

universe, forever.

Light from the night sky enlivens our universe..

Answer 2

I can think of two main effects: Energy and Pressure.

Explanation:

Light carries Photon energy proportional to its frequency `f` in the form given by Einstein's relationship (with a constant `h`):

`E=hf`

This energy will produce effects when interacting, say, with the components of a celestial body (planet, comet, even dust) promoting chemical reactions between elements and the possible formation of new compounds.

Another interesting effect is the Radiation Pressure associated with the propagation of electromagnetic radiation; basically, light can...push...object!
You can see this effect observing the direction of the comets' tail when travelling near the Sun: the plume of particles forming the tail of the comet is pushed away by the Sun's radiation in a radial direction from the Sun!

This pressure will affect clouds of dust and gas (as a current in a river or lake), possibly promoting local condensation of matter to create nuclei for the future formation of stars (the small aggregates of matter will now have a sizeable gravitational force able to further attract matter around them).

Hope it helps; it is the best I could think of.