Here is a deep photo of the NGC 7771 galaxy group. This dramatically shows that both nearby interstellar and inter-galactic space is filled with dust, gas, dwarf stars, soot, and matter... space is not empty. Click HERE.

All of this material attenuates starlight. Closer to home, as the Earth and Sun pass through local clouds like this, the light from the Sun is dimmed slightly (or may seem to brighten if we emerge from a stellar cloud). This brightening and dimming can have a significant impact on Earth's weather and climate.