Why can't you see geostationary satellites with your eyes?

They are about 36,000 km away — roughly 85 times farther than the ISS — so their reflected sunlight is thousands of times fainter than a low satellite's.

Several Indian satellites work from geostationary orbit, including EOS-05 (GISAT-1A), launched in September 2026. ESA describes this orbit as 35,786 km above the equator, where one orbit takes 23 hours 56 minutes 4 seconds — the same time the Earth takes to turn once. So these satellites appear to hang still over one spot.

You might expect them to be easy to see: they never move, and many are large. But they never appear in this site's pass lists, and the reason is distance.

ground ISS: 420 km geostationary: 35,786 km about 85 times farther so about 7,000 times fainter
Drawn to scale: the ISS at about 420 km is a sliver next to the 35,786 km climb to geostationary orbit. Being about 85 times farther makes a satellite there about 7,000 times fainter.

Worked example: the ISS versus EOS-05

The ISS orbits about 420 km up. EOS-05 (GISAT-1A), launched in September 2026, sits about 35,790 km up. That is roughly 85 times farther.

Reflected light falls off with the square of the distance. 85 × 85 ≈ 7,200, so the same satellite at geostationary height would look about 7,000 times fainter than overhead in low orbit. On the magnitude scale that is about 9.6 magnitudes fainter. A geostationary satellite would need to be extraordinarily reflective to reach the naked-eye limit; in practice they need a telescope.

Other reasons they stay hidden

  • They do not move. A slow, steady point is how you normally spot a low satellite. A geostationary one sits still among the drifting stars, looking like a faint star itself.
  • They sit low for northern India. They are lined up over the equator, so from Delhi (about 28.6° N) they appear well down in the southern sky, where city haze is thickest.
  • This site filters them out early. Before predicting passes, it drops anything that orbits fewer than 11 times a day. A geostationary satellite orbits about once a day. These satellites still have their own pages and estimated positions on this site; they just never appear as passes.

You can still follow them on the globe: pick a geostationary satellite such as EOS-05 or a GSAT and watch its estimated longitude barely change while the ISS crosses whole continents.

See it live

Select a geostationary satellite such as a GSAT: its estimated position stays over the equator at almost the same longitude, while the ISS sweeps past. Open the live globe

Key facts

  • Geostationary altitude: 35,786 km; period 23 h 56 min 4 s (ESA).
  • EOS-05 (GISAT-1A): 35,777 × 35,793 km, inclination 3.4°, period 1,436.03 minutes (CelesTrak).
  • A geostationary satellite is about 85 times farther away than the ISS.
  • Distance alone makes it about 9.6 magnitudes fainter than the same object at 420 km.

Go deeper

Use the inverse-square law in magnitude form: Δm = 5 log₁₀(ρ₂ / ρ₁).

From 420 km to 35,786 km: Δm = 5 log₁₀(35,786 / 420) = 5 log₁₀(85.2) ≈ 5 × 1.93 ≈ 9.65 magnitudes. In brightness, 10^(9.65/2.5) ≈ 7,300 times fainter.

Compare with the standard magnitude used by this site, defined at 1,000 km and half-phase. A satellite at 35,786 km is already 5 log₁₀(35.786) ≈ 7.8 magnitudes fainter than its standard magnitude, before any phase effects. Even an object with the ISS's standard magnitude of −1.3 would come out near +6.5 — beyond the roughly +6 limit of a truly dark sky and far beyond the 4.5 limit this site uses for Indian cities.

The actual range from an observer is a little more than the altitude unless the satellite is at the zenith, which only happens on the equator. From Delhi (latitude φ ≈ 28.6°) looking due south at a satellite on the same longitude, the elevation is given by tan E = (cos φ − R/r) / sin φ, with R/r = 6,378 / 42,164 ≈ 0.151: tan E = (0.878 − 0.151) / 0.479 ≈ 1.52, so E ≈ 57°. Farther east or west along the arc, the elevation drops towards the horizon.

The site's candidate filter reads mean motion from columns 53–63 of TLE line 2 and drops objects below 11 revolutions per day, which removes the whole geostationary belt (about 1.0027 rev/day) and the navigation satellites in medium orbits.

Check yourself

Why does a geostationary satellite appear to stay still in the sky?

Its orbital period matches the Earth's rotation (23 h 56 min) and it orbits over the equator in the same direction the Earth turns, so it keeps pace with the ground below.

A satellite is moved from 400 km to 4,000 km range. By how many magnitudes does it fade?

Δm = 5 log₁₀(10) = 5 magnitudes, a factor of 100 in brightness.

From Delhi, in which part of the sky do geostationary satellites lie?

In the southern sky, along an arc above the equator, because Delhi is about 28.6° north of the equator.

Sources

  1. Types of orbits — European Space Agency
  2. SATCAT record: EOS-05 (GISAT-1A) (100607) — CelesTrak
  3. SATCAT record: ISS (ZARYA) (25544) — CelesTrak
  4. The Brightness of VisorSat-Design Starlink Satellites (A. Mallama, 2021) — arXiv
  5. The Astronomical Brightness Scale — Space Academy