What Is a Satellite Pass? How to See Satellites

📘 Definition

A satellite pass occurs when an orbiting spacecraft rises above the local horizon, transits the sky, and sets below the opposite horizon from an observer's perspective. For visual observation, the satellite must be sunlit while the observer is in darkness — a condition met during the hours around sunrise and sunset. Pass characteristics include: maximum elevation (the highest point above the horizon, in degrees — higher is better for visibility and radio contact), duration (typically 2–10 minutes for LEO satellites), apparent magnitude (brightness — the ISS can reach magnitude −4, brighter than Venus), and direction (rise/set azimuth). For amateur radio operators, pass predictions also include Doppler-corrected frequencies, antenna pointing angles, and communication windows. Predictions are computed from TLE data using SGP4 propagation.

2–10 minutes (LEO)

Typical Duration

Up to magnitude −4

ISS Brightness

1–2 hours after sunset / before sunrise

Best Viewing Time

TLE data + SGP4

Prediction Source

Understanding Satellite Pass

How to See Satellites

Satellites are visible when they reflect sunlight while the observer is in darkness — this occurs during the 1–2 hours after sunset or before sunrise (twilight). The satellite appears as a steady, bright point of light moving smoothly across the sky (unlike aircraft, which blink). The ISS is the brightest and easiest to spot; Starlink trains (shortly after launch) are dramatic chains of lights. Use Orbital Radar's pass prediction tool to find passes for your location, with sky charts showing the exact path across the sky.

Radio Passes

For amateur radio operators, a satellite pass is a communication window. As a radio-equipped satellite rises above the horizon, operators can transmit and receive through its transponder or repeater. The challenge is Doppler shift — the satellite's motion causes the received frequency to shift higher on approach and lower on departure. Orbital Radar's radio pass tool provides real-time Doppler-corrected frequencies, antenna pointing data, and Maidenhead grid references for contacts.

Pass Quality

Not all passes are equal. Maximum elevation determines visibility and signal strength: a pass peaking at 10° above the horizon is low, brief, and dim, while one reaching 70–90° (overhead) is long, bright, and ideal for both visual observation and radio contacts. Predictions are accurate to within a few seconds for well-maintained TLE data, though atmospheric drag variations can cause timing shifts of 1–5 seconds for very low-orbit objects.

Frequently Asked Questions

How do I see a satellite? ▼

Look up during the 1–2 hours after sunset or before sunrise, when the sky is dark but sunlight still illuminates objects in orbit. A satellite appears as a steady, bright dot moving smoothly across the sky — not blinking like an aircraft. Use Orbital Radar's pass prediction tool to find exactly when and where to look from your location. The ISS is by far the easiest to spot.

Why can't I see satellites at midnight? ▼

In the middle of the night, satellites in low Earth orbit pass through Earth's shadow — they are not illuminated by the Sun and therefore invisible. Only during twilight (1–2 hours after sunset or before sunrise) are LEO satellites sunlit while your location is dark enough to see them. Higher-altitude satellites (e.g. GEO) can be visible longer but are much fainter.