Zodiacal light is a glow visible in spring (evening) or fall (dawn). It is caused by the reflection of sunlight by microscopic dust. How to observe the zodiacal light?
The month of March 2023 lends itself well to observing the zodiacal light, among other astronomical phenomena. From March 15, and for a week, the evenings are conducive to looking for this amazing glow in the sky, just after sunset, towards the west.
Where does this brightness come from? What advice to follow to observe it well? Here is everything you need to know about the zodiacal light, to watch it in the best conditions, in spring and autumn.
What is Zodiacal Light?
This observable glow is explained by the reflection of sunlight by space dust. These particles mainly come from comets that have come close to the Sun and ejected material. ” You have to imagine that this microscopic dust is rough. Think of the Moon: when it is lit from the front, it is brighter. Here is the same phenomenon. », Explains Jean-Luc Dauvergne, member of the French Association of Astronomy. The Paris observatory indicates that the zodiacal light can still represent 60% of the luminosity of a moonless night.
How to observe the zodiacal light?
In the days surrounding the vernal equinox, you can attempt to see the zodiacal light in the evening. Observation is usually possible during the first 10 days of April », Continues the representative of the French Association of Astronomy. Same thing around the autumnal equinox, in September.
Watching the zodiacal light requires a bit more anticipation than simply gazing at the Moon. Moreover, this glow is easier to see when our natural satellite is absent from the sky (at the time of the new moon). ” The zodiacal light is a rather faint glow. You must move away from any source of light pollution. If one manages to find a sufficiently dark place, then it can almost become awkward “, continues the specialist. We will therefore have to forget the big cities…
The zodiacal light is visible above the western horizon in spring and above the eastern horizon in fall. Jean-Luc Dauvergne advises looking for a ” oval glow truncated by the horizon at dusk. In astronomy, this term is used to refer to the period which precedes sunrise or follows its setting. The center of the sun is 12° to 18° below the horizon. The best time to observe the zodiacal light should be around 1 hour after sunset, or 1 hour before (depending on whether you are trying to observe it in March/April or September/October).
Where should you go to hope to see this light show? In France, people living on the ” Atlantic rim are well placed in the spring (because they are to the west) to attempt to observe the zodiacal light. Provided, however, that you are not in a big city, ” like burgundy “says Jean-Luc Dauvergne. In autumn, as you will have understood, people living in the east of France are in a better position.
Why don’t we see the zodiacal light more often?
Why is it visible at very specific times, in spring (in the evening, at dusk) and in autumn (in the morning, before dawn)? This corresponds to the times when the zodiac is perpendicular to the horizon.
In astronomy, the zodiac is the place in the sky in which we see the movement of the Sun (which seems to pass through 13 constellations in a year), the Moon and the planets. The zodiac extends around the ecliptic, that is to say the trajectory drawn by the Sun each year, seen from Earth.
” Depending on the tilt of the Earth on its axis, the zodiacal light will be more or less straight with respect to the horizon “says Jean-Luc Dauvergne. In other words, the ecliptic must form an angle with the horizon that is as perpendicular as possible. From Europe, these conditions are met in spring and autumn.
You now have all the keys in hand to try to see the zodiacal light, after sunset or before sunrise depending on the time of year. Good watching!
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