Now.
You are reading this in the present, whatever that means. The screen in front of you sends light that left it a fraction of a nanosecond ago, close enough to now that no one would quibble.
A few feet away, a lamp. Its light took a few billionths of a second to cross the room. Old news, technically, but too recent to matter.
Look up at a bird passing overhead. The light bouncing off its wings is already a little stale by the time it reaches your retina, delayed by the time it takes light to cross that distance. Millionths of a second. Nothing changes in that gap.
The moon. Its light left about one and a quarter seconds ago. When you see the moon, you are seeing where it was slightly more than a second in its own past, not where it is now.
The sun. Eight minutes and twenty seconds. If the sun vanished this instant, the sky would carry on lying to you for a little over eight minutes before going dark.
The nearest star beyond our own, a small point of light visible from the southern hemisphere. Roughly four years old, its light. Whatever is happening there now, you will not know until around 2030.
The center of our galaxy. About twenty-six thousand years. The light now falling on your eyes left that crowded core of stars before agriculture existed anywhere on Earth.
The Andromeda galaxy, the faint smudge some clear nights let you find without a telescope. Roughly two and a half million years. That light set out before anything recognizably human was walking upright.
A galaxy near the edge of what our best telescopes can resolve. Something on the order of thirteen billion years. That light left its source when the universe itself was young, only a few hundred million years past its beginning. The galaxy that made this light may no longer exist in any form its ancient self would recognize. What we are seeing is not a place. It is an event, arriving late.
This is what astronomers mean by lookback time: the delay between something happening and its light reaching an observer, a delay set entirely by distance and the fixed speed of light. It is not metaphorical. It does not require philosophy to work. It is arithmetic, distance divided by a constant, and it applies to the lamp beside you exactly as it applies to a galaxy near the edge of the observable universe. The only difference is scale.
There is a temptation to call the universe a kind of memory, storing its own past for us to read in starlight. I understand the pull of that image, but it overstates the case. Memory implies a rememberer, something that holds a past and can be wrong about it, revise it, forget it. The sky does none of this. It does not keep anything. It simply has not yet delivered what left long ago. The light is not a record being consulted. It is a delivery still in transit.
What is true is narrower and stranger than memory, and I think better for being narrower. When you look outward, you are also looking backward, by an amount fixed for every distance, all the way down to the near edge of the room you are sitting in. Nothing up there is being remembered. It is only, finally, arriving.