There are some topics that get a little frustrating in their pedantry, but can really draw attention to the grand scope and mechanics in our Universe. This is definitely one of them.
We know looking through a telescope is like looking into the past, both out from and towards our Earth. We know if alien ships were looking at the Earth right this moment from distant star systems they'd could well be watching dinosaurs chomping on each other's adorable little faces.
So how do we know what's actually going on right now in other parts of the Universe? No matter how close together, the real challenge of defining "now" simultaneously for two different spots in the Universe is that these points are always separated by a bit of distance. Since nothing can travel faster than light, it will always take a some time for an indicator that an event has "happened" to reach you.
That's a relative question. To read more and view the video, click here.