There are people living in orbit above Sweden, and on the right evening you can watch their spacecraft go past with no equipment at all. You just have to know when to look, and the timing is stricter than most people expect.
Satellites do not glow. They are visible only because they reflect sunlight, exactly as the Moon does. That single fact sets every rule about when you can see one.
Three conditions have to line up at the same moment:
Since the space station orbits at around 400 kilometres, the Sun is still shining up there for a while after it has set for you. That mismatch is the whole trick, and it leaves a window of roughly one to two hours after sunset and the same before sunrise. Later in the night the station enters the Earth's shadow and disappears, however clear the sky.
The space station is the brightest artificial object in the sky, at its best rivalling Venus. It appears low down, usually in the west or south-west, and glides steadily upwards and across.
The clearest tell is that it does not blink. Aircraft have flashing navigation lights and, near enough, engine noise. The station has neither: a steady white point moving with a purposeful, unhurried pace. It crosses in two to six minutes depending on how high the pass goes.
Very often it does not reach the far horizon. Halfway across it fades over a few seconds and vanishes into nothing. That is it entering the Earth's shadow, and it is worth watching for on purpose.
Passes are not equal. The number that matters is the maximum elevation, how high above the horizon the station climbs.
A pass topping out at 10 or 15 degrees is a brief, dim thing low over the rooftops. One reaching 60 degrees or more goes almost overhead, stays visible for several minutes and is unmistakably bright. If you can only go out once, wait for a high one.
The station's orbit is tilted about 51.6 degrees to the equator, which is why Sweden gets passes at all but never sees it directly overhead. The further north you are, the lower in the sky it stays.
Satellite brightness is given as a magnitude, an old astronomical scale where lower numbers mean brighter objects and negative numbers mean very bright indeed. The brightest star in the night sky sits at about -1.5. The space station can reach -4, brighter than anything except the Moon.
Most other satellites are far dimmer, magnitude 2 to 4, which is visible from a dark spot but easily lost from a lit street. The station is the reliable one for anyone who has not done this before.
Once you start looking you will notice how busy the sky is. On a dark night away from town, a patient watcher will see several satellites an hour drifting past.
The odd one out is a Starlink train: a line of evenly spaced lights following the same track in single file. These are newly launched batches that have not yet spread into their final orbits, and the formation only holds for a few weeks after each launch. It is a genuinely strange sight the first time, and it accounts for a good share of the UFO reports that follow every launch.
You need no equipment, but three things help. Get away from direct streetlight so your eyes adjust. Check the cloud forecast, since a clear sky matters more than anything else. And be outside a minute or two early, because the pass starts on time and does not wait.
Binoculars are optional and mostly unhelpful, since the station moves too fast to track comfortably. Watch it with your eyes instead.
Nollan.se shows the next visible passes over your town, with time, direction and maximum elevation, so you know both when to go out and where to look.
Aircraft blink, the space station does not. It appears as a single steady white light, as bright as the brightest planets, moving smoothly across the sky without flashing and without any sound. It takes a few minutes to cross and often fades out mid-sky rather than reaching the horizon.
Because you need to be in darkness while the satellite is still in sunlight. Around midday the sky is too bright, and in the middle of the night the satellite is in the Earth's shadow. That leaves a window of an hour or two after sunset and before sunrise.
It has flown into the Earth's shadow. The satellite does not produce light of its own, it only reflects sunlight, so when it crosses the shadow line it fades from view within seconds. Seeing it disappear in a clear sky is normal and slightly eerie.
About 28,000 kilometres per hour, which is one orbit every 90 minutes or so. From the ground that works out as a steady, purposeful glide across the sky in two to six minutes, noticeably faster than an aircraft but not startlingly so.
Almost certainly a Starlink train, a batch of satellites recently launched and still flying close together before spreading out. They look like a string of evenly spaced lights following each other along the same path, and the sight only lasts for a few weeks after each launch.