Why the ISS is only visible at dawn and dusk

You can only see the ISS around dawn and dusk because it makes no light of its own. It shines by reflecting sunlight, so your sky has to be dark while the station, about 400 km up, is still in sunlight. That overlap usually comes in a window of an hour or two after sunset and before sunrise; later in the night the station is in Earth's shadow too.

We know this rule because we had to write it as code. Orbit, our free Android app, works out visible passes on your phone, and every pass it shows has cleared the same three tests. Below are the tests, then a month of real passes over Bengaluru, where our studio is, computed on 20 October 2026.

What has to line up for you to see the ISS?

Orbit keeps a pass only if all three of these hold at its highest point:

1. Your sky is dark. The Sun is more than 6 degrees below your horizon. That is the end of civil twilight, when the National Weather Service says the brightest stars and planets can be seen.
2. The station is in sunlight. It is outside Earth's shadow, which Orbit models as a cylinder as wide as the Earth, pointing away from the Sun.
3. It climbs high enough. The pass peaks at least 10 degrees above the horizon, about the width of a fist held at arm's length. Lower passes stay down among rooftops, trees and haze.

The first two pull against each other. A dark sky needs the Sun well below your horizon, and a sunlit station needs it not too far below. The overlap exists because of height. On 20 October, CelesTrak's orbital elements (the published numbers that pin down the station's orbit) put the station about 420 km up, so it still catches the Sun after the ground beneath it has gone dark, the way a mountain peak stays lit after the valley falls into shadow.

Is the ISS visible at night?

Yes, but usually only in the first hour or so after dark and the last hour or so before dawn. From about 420 km up, the station stays in sunlight until the Sun is roughly 20 degrees below the horizon for someone standing directly beneath it. Past that, a station straight overhead is in Earth's shadow.

In Bengaluru on 6 November, the Sun sets at about 17:52 and is 20 degrees down by about 19:15. That means an overhead pass can only be seen between about 20 and 80 minutes after sunset (before that the sky is too bright), and the same before sunrise. Low passes in the west after dusk, or in the east before dawn, stay lit a little longer, because the station is then over ground where the Sun set more recently or will rise sooner.

You will not see the station late at night here: by midnight the Sun is more than 80 degrees below the horizon. The station still flies over. It circles the Earth about every 90 minutes, 16 times a day, and in our 30-day run it climbs at least 10 degrees over Bengaluru 76 times.

In 36 of those 76 passes the station is in Earth's shadow at its highest point, with the sky already dark. One of them peaks at 75 degrees, nearly overhead, at 22:12 on 29 October, and nobody will see it.

The same 20-degree limit explains why people far from the equator can see the station around midnight in midsummer. Their Sun never sinks that far below the horizon, so a station overhead stays in sunlight all night.

Can you see the ISS during the day?

Not with your eyes. NASA says the station is not bright enough to see during the day, unlike the Moon. It is up there in daylight all the same: 32 of the 76 passes in our run happen in daylight, including the highest of the month, 82 degrees at 14:22 on 18 November.

Is the ISS visible every night?

No. Over Bengaluru, only 8 of the 76 passes in our 30 days pass Orbit's three tests, and all 8 fall between 4 and 9 November. None does in the two weeks before that, or after it to the end of the run. NASA puts the range at anywhere from one viewing chance a month to several a week, in the same Spot the Station FAQ.

These are the eight, with the details Orbit shows on each pass card. The two best both fall on 6 November, one before dawn and one after dusk.

For Mumbai, Delhi and Kochi, and why their times differ from Bengaluru's, see our guide to seeing the ISS from India.

Why do passes come in runs, with weeks of nothing?

Because the pass times slide earlier every day. Take the evening passes that climb to about 75 degrees, four days apart: 22:12 on 29 October, 20:38 on 2 November, 19:05 on 6 November, 17:31 on 10 November. Each one comes back about an hour and a half earlier than the last, which works out to roughly 23 minutes a day.

On 29 October and 2 November that pass comes after dark, with the station already in Earth's shadow. By 10 November it comes before sunset. Only around 6 November does it land in the dusk window. The morning passes go through the same window that week from the other side: daylight on 29 October and 2 November, visible on 6 November, and in shadow at the peak by 10 November.

At 23 minutes a day, a pass takes about two months to slide all the way round the clock. That is the station's orbit turning slowly relative to the Sun, a cycle the team running the AMS-02 particle detector on the station puts at 60 days. Each time the pass times sweep across your dawn or dusk, you get a run of visible passes, then a wait. On 20 October's elements, Bengaluru's next run starts around 3 December, a date that will move as the orbit is updated.

The times also move when the orbit itself changes. Visiting spacecraft fire their engines to raise the station from time to time; on 27 August 2026 a Cygnus XL cargo ship attached to the station burned for 20 minutes and 43 seconds. That is why Orbit refreshes its orbital elements daily and looks only four days ahead, and why the dates above may still move.

Why does the ISS disappear in the middle of the sky?

It has flown into Earth's shadow. You are still looking at the right spot, but there is no sunlight left on the station to reflect. NASA's FAQ gives the same reason for passes that look short: the station moving into or out of Earth's shadow.

The evening pass on 6 November shows it well. It rises in the south-west at about 19:00 and climbs to 75 degrees at 19:05. Less than a minute later, about 45 degrees up in the north-north-east, it fades out. It sets in the north-east at 19:10, unseen.

Morning passes can do the reverse and appear partway up the sky as the station comes out of the shadow. On 7 November the morning pass lights up at about 04:57, already 22 degrees high.

One detail of how Orbit decides: it runs its three tests at the highest point of the pass only. That keeps the rule simple, but a pass that is in shadow at its peak gets left off even if part of it is sunlit: an evening pass that fades before it reaches its peak, or a morning pass that lights up on the way down.

The best of these in our run is the 9 November morning pass. It comes out of the shadow right at its peak, 40 degrees up in the south-west at about 05:00, and stays in sunlight above 10 degrees for about three minutes. Our run leaves it off the table, but it sits so close to the line that Orbit may list it as a Good pass, depending on which half-minute it happens to sample.

How do you read a pass prediction?

Orbit shows each pass as a small card with the date, a rating and these four details.

Go out a few minutes early, face the rise direction, and look a little above the horizon for a steady light climbing the sky.

How do you tell the ISS from a plane?

NASA describes the station as looking like a plane or a very bright star moving across the sky, with three giveaways: it has no flashing lights, it never changes direction, and it moves faster than a typical airplane. If it blinks, it is a plane. If it is steady, holds a straight line and follows the path your prediction gave, it is the station.

How bright is the ISS?

NASA calls it the third-brightest object in the sky, and described one good pass as shining as bright as Venus. At its best it outshines every star, so city lights are no obstacle.

How bright a given pass looks depends a lot on distance. Overhead, the station is about 420 km from you. At 10 degrees up it is about 1,500 km away, three and a half times farther, which cuts the light reaching you to about a twelfth before the thicker air near the horizon dims it further.

Getting a heads-up

Orbit runs all of this on your phone. It refreshes the station's orbit from CelesTrak, works out the next visible passes for where you are, and alerts you 12 minutes before one rises. It is free on Google Play, with no ads and no account. If you are in India, our guide to seeing the ISS from India covers directions, cities and timing.

On a Mac, Orbit: Live Sky Desktop ($6.99 on the Mac App Store) puts the real sky on your desktop. During each visible pass the station crosses it, and an alert comes five minutes before the station rises.

We built Orbit with Claude Code and Codex, and Falcon wrote the physics engine himself.