Sure . . . intervening objects (asteroids, for instance) that intercept the path(s) of traveling light (photons) will absorb (and some reflection) a portion of the light, similar to putting your hand in front of your face will block (~ absorb?) the light from a flashlight. In the case of your post (light source transmitting light to earth with intervening asteroids), that portion of the light intercepting asteroids (or interstellar dust, gas, etc.) will interact with the transient light (beam) and reduce the "total" energy of the "total" originating light packet. This energy differential is mostly 'transferred' to the interacting particles, and thus is actually NOT lost - this is how 'light sails' work, BTW. These interaction events are miniscule in the overall scheme of things under practical conditions. To become significant, light intensity, duration, and mass (of impact object) are the most important considerations. I have not considered other esoterics such as light frequency, coherence, gravity, etc. I'm sure there are additional considerations that other readers might focus upon. Possible effects on astronomical measurements? Decrease in light intensity with distance, gravity lensing and other mass interactions, red or blue shifting depending upon direction of light source movement relative to observer (earth). Lesser effects (I suppose): perhaps secondary fluorescence?, thermal effects on objects?, etc.