From the Poetic Asides blog:
For today’s prompt, write a looking back poem. Of course, some people just glance over their shoulders, and others stop and turn all the way around. Some look back in time and weigh their successes and failures, evaluate things they could do better. Some claim they never look back. Whatever your stance on looking back, capture it in a poem today.

Telescopes are Time Machines

Each time I look up,
I’m looking back.

The stars, so distant,
their light takes years
to reach my telescope,
I am literally looking back
in time, seeing an image
from centuries long past.

With sufficient technology,
well beyond what we have now,
I could watch life arise
on a distant planet,
or burn itself out.

I don’t even need optics,
just the knowledge
of where to look
and these weak human eyes
can capture light
that erupted millennia ago.

Since light travels
at a limited speed,
technically speaking,
I am always looking back.

I never see you as you are,
I only see you as you were.