A train of satellites
Each Falcon 9 launch releases a few dozen Starlink satellites together, low above the Earth. For the first days they fly one behind the other on almost the same orbit, which is why they cross the sky as a line of dots.
Starlink train tonight: when to see it
A line of bright dots crossing the sky in single file, one after another: a Starlink launch from the last few days. Below are the newest launches and when their train passes over you.
Next passes of the newest launches
Over the next 72 h, from fresh CelesTrak elementsWhat you saw, and when to look
Only at dusk and dawn
A satellite shines only by reflecting sunlight. It is seen when it is still in the Sun while your sky is already dark: in the hour or two after sunset or before sunrise. A pass in the middle of the night is in the Earth's shadow and invisible.
A few days, then it fades
The satellites then climb to their working altitude, spread out along the orbit and grow fainter. A train is most striking in its first days and is rarely seen as one after a week or two.
What these predictions are worth
A satellite appears here once CelesTrak has catalogued it, usually a day or more after launch, so the very first evening of a train is often missing. Elements of a satellite that is still raising its orbit age quickly: an evening's times can shift by a minute or more, so step outside a few minutes early.
“Potentially visible” means sunlit while the Sun is at least 6° below your horizon; clouds and city light are not part of the calculation. How the passes are computed and checked is on the methodology page, and any other satellite is a search away on the satellites page.