at what point does 'then' become 'now?'

In the night, beyond the street lamps outside the porch, I can catch sight of a twinkling star. Twinkle, twinkle. Who knows what massive explosion or passing shadow twinkles its twinkle? And then, as well, who knows when precisely the twinkling activity occurred ... was it yesterday or the day before ,,, it's so far from there to here: Who knows the 'when' of it all?

I sit on the porch now.

It twinkles then... a gazillion miles away. It takes time for the activity to reach forward to the likes of me.

At what point does then become now?

It's a past twinkling in a present. There's no separation and yet separation separates the scene -- me on the porch, twinkling of the past infusing the present which is none other than the past.

If the past does favors for the present, what favors does the present do for the past ... if any?

Time is a strange and fractious cuss ... though I have a hard time imagining that the stars or the porch are discommoded.