many thanks to the three of you.

those were 3 quite distinct answers and all contributed to me better understanding the question i was asking. (i read the article on Cepheids also - heavy theory there)

so we can reasonably conclude that our physics of EM radiation is sound, although the possibility of light speed variances still exist, the variances over the distance may be considered negligible.

and we can also determine distance based on the constant of light.

But the mind boggles with the thought that the way the Universe looks now is obsolete. do you think it would be possible to somehow calculate a stars or galaxys vector of travel and compute all that data to produce an actual image of the Universe?