Space Station Shines Over Serbia as Perseids Near Peak

On the night of July 22, many observers across Serbia saw the International Space Station (ISS) with the naked eye, and social media soon filled with photographs of the pass. The station crossed the sky as a distinctly bright point that moves steadily and does not twinkle, which sets it apart from aircraft and from stars. No equipment was needed to see it, only a clear sky and the right moment.

What makes the ISS so easy to spot is its size and the height of its orbit. The station circles Earth at roughly 400 kilometers altitude and, although it emits no light of its own, its large solar panels reflect sunlight toward observers on the ground. That is why it is visible only during certain windows, usually shortly after sunset or before sunrise, when the sky above the observer is already dark while the station high above remains in sunlight. A pass lasts a few minutes, and during that time the station moves faster than anything else in the sky.

Why is the ISS visible to the naked eye?

The ISS is the brightest artificial object in the night sky and in apparent brightness often outshines even the brightest stars. It travels at an average speed of about 28,000 kilometers per hour and completes one orbit of Earth in roughly 90 minutes, which means it circles the planet more than fifteen times a day. For observers this creates several opportunities, but only those in which the geometry of the Sun, the station and the observer allows a reflection result in a visible pass.

Visibility windows are not the same every night and shift from day to day. Through its Spot the Station service, NASA lets you check the exact time, direction and height above the horizon for a specific location, so a pass can be planned in advance. Data for Serbia can be found by entering the nearest large location, and a pass is easiest to follow when the station climbs higher above the horizon, away from light pollution and objects that block the view.

The station’s pass coincided with the period when one of the year’s best-known meteor showers is active. The Perseids run through July and August, when Earth crosses the trail of dust left behind by comet Swift-Tuttle. The particles, often no larger than a grain of sand, enter the atmosphere at high speed and burn up, leaving the short bright streaks observers know as shooting stars.

How and when to watch the Perseids?

The Perseids reach their maximum around August 12 and 13, when the number of visible meteors under ideal conditions can be far higher than during the rest of the active period. No telescope or binoculars are needed, because meteors appear at random across the whole sky, so the naked eye and a wide field of view give the best results.

The most important condition is a dark sky. City lighting sharply reduces the number of visible meteors, so heading to locations far from large settlements, under a clear and cloudless sky, is recommended. Good visibility also depends on the phase of the Moon, since bright moonlight washes out fainter meteors. Observers are advised to let their eyes adjust to the dark for at least twenty minutes and to watch a wide part of the sky rather than a single point.

Unlike one-off astronomical events, both ISS passes and the Perseid peak repeat predictably from year to year, so they can be planned even with little experience. It is worth noting that the hourly meteor count often quoted for the Perseids applies to ideal dark-sky conditions, while the number actually visible from a site near a city is usually lower. Will you head out of town this year to catch the Perseids at their peak?