Is the ISS Visible Tonight?

Is the ISS Visible Tonight?

The brightest “star” that moves may be a spacecraft. The station is only easy when your sky is dark enough, the ISS is still sunlit, and clouds are not solid. Timing beats luck.

ISS Pass Predictor · Tonight Score · Stargazing Weather

Why you can see satellites at all

Low-Earth-orbit satellites reflect sunlight. You see them when you are in darkness (or twilight) and the satellite is still lit, which is why passes cluster in the evening and the morning. Mid-night eclipses are common: the craft flies into Earth's shadow and fades out.

At its best the International Space Station reaches about magnitude -3.9 and rivals Venus; most good passes outshine every star. From Guyana (about 6°N), passes can go high overhead, depending on the orbit plane that week.

Earth and its shadow to scale: why a station 420 km up shines in a dark sky, and when it goes dark.

One evening pass over Georgetown that fades out high in the sky, and the reason: the station flies into Earth's shadow, which reaches overhead once the Sun is about 20° down.

At 01:30 a high pass is labelled Eclipsed. Why can't you see it?

• It is too far away at night
• The station is in Earth's shadow, so it is not lit (the right answer)
• Its lights are switched off after midnight
• The sky is too bright

You see the station only by reflected sunlight. In the middle of the night it is usually inside Earth's shadow, so passes cluster in the evening and the morning.

What makes a pass spottable

• Peak after local sunset or before sunrise (dark or twilight sky).
• Station still in sunlight (not eclipsed by Earth).
• High enough elevation that trees and buildings do not block it. The predictor's “Next worth going out” card asks for a peak of at least 15° and a pass of at least 3 minutes.
• Clear enough sky along the track. Heavy cloud or thick haze can hide even bright passes.
• Face the predicted start bearing: the compass azimuth at rise tells you where to look first.

Magnitude estimates are approximate, and haze and light pollution dim the view.

Reading the visibility labels

ISS Pass Predictor labels every pass:

| Label | Meaning | |------|---------| | Good to spot | Your sky is dark (Sun more than 6° below the horizon) and the station is sunlit. Best chance for naked-eye spotting. | | Twilight | The Sun is between about 1° and 6° below the horizon. The sky is still bright, but the ISS is often easy anyway. | | Daylight | The Sun is up, so the sky is too bright to spot the ISS. | | Near sun | The ISS is within 35° of the Sun while the Sun is up or less than 12° below the horizon. Do not hunt near the Sun. | | Eclipsed | Your sky is dark, but the station is in Earth's shadow, so it is not lit. |

The coming passes for Georgetown or Lethem as the predictor finds them, with each pass's label and its path on a compass dial.

Weather gate

If Tonight Score says Skip, treat faint passes as optional. A bright pass (about Sirius class or brighter) can still punch through thinner gaps. Open hourly Stargazing Weather before you wait outside for ten minutes of sky.

City hub pages show the next spottable pass with a weather note when the score is Skip.

Step-by-step

1. Open ISS Pass Predictor and set your location.
2. Prefer passes labeled Good to spot or Twilight with solid max elevation.
3. Cross-check Tonight score and cloud timing.
4. Stand outside a few minutes early, facing the start bearing. The ISS looks like a bright, steady moving star with no blinking wing lights.

Photographing a pass

• Use a wide lens on a sturdy tripod, focused at infinity, and include a landmark for scale.
• Start with 30-second test exposures around ISO 400 and f/4: the station draws a long streak. Exposures of 1 to 5 seconds show only a short dash, because a high pass crosses the sky in a few minutes. Video works for live view.
• Shoot consecutive frames through the pass and stack them to join the whole path; the small gaps between frames show as a dashed line.

How long a streak the station draws for your exposure and how high the pass climbs, on a 24 mm frame.

You shoot a high pass with 3-second exposures. What does the station draw in each frame?

• A long streak across the frame
• A short dash, about 3° long (the right answer)
• A sharp dot
• Nothing: it is too fast to record

A high pass crosses about a degree a second, so 3 seconds draws a dash of about 3°; 30 seconds draws a long streak.

Limits

Predictions come from orbital elements that age, so refresh predictions for passes days out. Weather still cancels. Iridium flares of old are mostly gone, and many dimmer satellites need darker sites.

FAQ

Why did the app say a pass but I saw nothing? Daylight, eclipse, low elevation, or cloud along the track. Apps predict geometry. Weather still wins.

Is Spot the Station better? NASA now sends pass alerts only through its free Spot the Station app (its email and text alerts ended in June 2025). AstroPhotosGY adds a free browser table with visibility flags and shareable lat/lon links. See Free ISS Tracker Comparison.

Next

• How to Use ISS Passes
• ISS and satellites in Sky Events
• Tool: ISS Pass Predictor
• Weather: Stargazing Weather