Zodiac light, is sunlight scattered by particles of interplanetary matter in the plane of the ecliptic. These particles, measuring between 0.001 and 0.1 mm, originate mainly from comet tails, crumbling asteroids, but also from the "dusty" planet Mars. Because they are spread mainly in the plane of the ecliptic (the plane in which the Earth's orbit lies), the cone of light is projected onto the sky in the zodiacal constellations. This is where the name comes from. In areas near the equator, the zodiacal light is visible throughout the year, as it never forms such a small angle with the horizon that it disappears low above the horizon. From our latitudes, it can best be observed around the equinoxes., in the spring in the evening after dusk above the western horizon and in the fall, conversely, in the east in the morning before dawn. During these periods, the plane of the ecliptic at our latitudes forms the largest angle with the horizon, and the light is therefore most visible.

Light has fascinated people since time immemorial.. For many years, there was no clear scientific explanation for the unusual and blurred cone of light shining from behind the horizon in an otherwise starry sky, visible after dusk above the western horizon or, conversely, before dawn in the east. It was probably first noticed by the famous Italian astronomer Giovannni Domenico Cassini (1625–1712), who in 1683 mentioned the theory of sunlight scattering on dust particles. Other sources dispute Cassini's primacy and claim that the Swiss mathematician Nicolas Fatio de Duillier (1664–1753) publishing his work just a year later, in 1684. Either way, just three centuries later, the era of advanced photography arrived and the first relatively nice images of the zodiacal light cone were taken. Unfortunately, excessive harmful light pollution from cities has gradually made the phenomenon invisible from many places around the world.

Sir Brian May (born 1947), astrophysicist and guitarist with the band Queen, played a significant role in describing the phenomenon.. He began writing his dissertation on zodiacal light during his studies at Imperial College London at the turn of the 1960s and 1970s. In it, he dealt with the different speeds of particles in the dusty disk that causes zodiacal light due to the scattering of sunlight. However, at that time, the band Queen, of which he was a member, became very popular, so he interrupted his studies. It took him more than 30 years to complete his thesis! In 2007, he updated his thesis and successfully defended his doctorate.

Unfortunately, the light from the zodiac is approximately 70 times weaker than the sky in brightly lit cities., Therefore, it is necessary to find an observation point where there is no light pollution or fog. Clear weather is also required, of course. In the Czech Republic, the phenomenon can be observed, for example, in the Vysočina region, Šumava, Novohradské hory, Beskydy, Jeseníky, Manětínsko, and Orlické and Jizerské hory (where there are areas designated as darkness reservation in translation). In Slovakia, it can be found in mountainous areas such as the Low Tatras, Veľká and Malá Fatra, but also Muráňská planina and (especially) the Poloniny Dark Sky Park. So if you are near these areas or simply further away from large cities in general, These days, you can already see a fairly distinctive cone of light reaching up to 60° above the horizon at a time when the Sun has been below the horizon for more than an hour (i.e., around 7:00 p.m. CET and later).

Under ideal conditions (which prevail, for example, in high mountain areas in Chile), it is possible to see not only the cone of zodiacal light (which is actually rather a disturbing element in these areas), but also the weaker so-called zodiacal bridge connecting the eastern and western zodiacal cones, or a brighter spot in the zodiacal bridge called the zodiacal counterglow. This is a spot located on the opposite side from the Sun, where particles of interplanetary matter scatter the most light because they are "full moon." From our part of the world, these phenomena can only be observed on rare occasions, and then mainly through photography (especially in the aforementioned areas of dark sky).

The best time to see the zodiacal light will last until approximately March 20th, the date of the spring equinox. After that, the moon will once again begin to interfere with its light and the zodiacal light shines brightly. After dark, not far above the horizon, in the brightest part of the whitish cone, we can also find the planet Venus. High above the southern horizon in the constellation Gemini, the distinctive planet Jupiter is also visible. The zodiacal light will still be visible in April, specifically from April 3 to 19, but its angle to the horizon will slowly decrease and conditions for observation will deteriorate.

Of course, you can also photograph the zodiac light.. It is best observed approximately 1-2 hours after sunset (if the sun sets at 6 p.m., for example, the light is best visible between 7 and 8 p.m.). First, you need to find out the time of sunset for your observation location – for example, via this website. Then all you need to do is plan the right time for shooting. It is also important to have the western horizon as clear as possible, and it is ideal to shoot from an elevated position or hill. You will need a tripod and a large-format camera (SLR, mirrorless; a cell phone is definitely not sufficient) and a wide-angle lens of around 15 to 20 mm. The actual shooting is then simple – after dark, point towards the western horizon and frame more than 2/3 of the sky. For short exposures of around 15-20 seconds at a higher ISO and open aperture, gradually photograph the night sky focused on infinity. The darker it is, the more contrastingly the animal light will stand out in the photo as a bright blurred cone against the starry background. The sky in the images also features bright stars from the constellations Taurus, Orion, and (with a wide field of view) the Andromeda Galaxy. More experienced photographers can try point photography or panoramic shooting.

The zodiacal light is one of many interesting phenomena that we can observe in the Czech Republic during 2026. You can find the complete list of the most remarkable celestial phenomena we can look forward to in this article.

Contact details:

Mgr. Petr Horálek

RNDr. Tomáš Gráf, Ph.D.