How to Spot Starlink Satellite Trains in the Sky?

Why Can We See Starlink Satellites from Earth?

Starlink satellites, deployed by SpaceX to provide global internet access, are placed in low orbit (about 550 km altitude). Unlike stars that emit their own light, these satellites are visible because they reflect sunlight. This is why the best observation windows are just after sunset or just before sunrise: the observer is in darkness, but the satellites, still illuminated by the Sun, stand out as aligned moving stars against the sky.

The most impressive phenomenon remains the "train" of satellites. If these trains are particularly spectacular in the days following a launch (when the satellites are not yet dispersed), we can also observe bright lines in operational phase. Indeed, satellites in the same orbital plane can appear in a tight convoy depending on the observation angle, creating this string of bright pearls moving in single file.

When and Where to Look to See the Satellite Constellation?

Observing Starlink satellites requires no optical instrument, just a clear sky. There are two types of passes:

• Passes of "trains" of newly launched satellites: They are much brighter (easily visible like the stars of the Big Dipper or the North Star) and form a spectacular line. These passes are only visible for a few days after launch. Their formation changes rapidly. Day after day, the gap between them increases, the orientation of the group changes, until they reach their operational orbit.
• Passes of operational satellites: They are less bright (visible with a little attention) but very numerous. Their orbital configuration is stabilized. Each follows a precise and repetitive orbit.

Essential Tools to Not Miss Them

However, to avoid scanning the sky at random, it is essential to know the passing times, which vary depending on your geographical location. To know exactly the time of the next pass over your location, the use of digital tools is essential. Several applications and websites, using data from TLE elements (north American Aerospace Defense Command, providing orbital elements of objects in orbit), allow predicting passes with an accuracy of a few seconds.

• Find Starlink (new window): Simple and effective, just enter your location to get the list of upcoming bright passes.
• Heavens-Above (new window): A historic tool for satellite enthusiasts. It provides detailed star maps with the exact trajectory.

Table of Orbital Characteristics and Visibility of Starlink Satellites

The Future of Observation

It is estimated that the number of satellites in low orbit could exceed 100,000 by 2030. For professional astronomers, this represents a major challenge. Long exposures from telescopes are systematically streaked by the passage of these objects. In response, SpaceX is experimenting with anti-reflective coatings (such as "DarkSat" and "VisorSat") and attitude adjustments to minimize their albedo.

FAQ: Everything about observing Starlink satellites