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Zodiacal Light

Zodiacal Light – Facts that you didn’t know

The zodiacal light meaning is the false dawn when observed before sunrise. And it presents as a subtle, soft, roughly triangular white radiance visible in the night sky. It gives the impression of stretching from the direction of the Sun and following the zodiac. When crossing the ecliptic Earth’s orbital path around the Sun. The scattering of sunlight by interplanetary dust gives rise to this effect.

What is the Perfect Time to Observe Zodiacal Light?

Zodiacal light can be seen only during twilight. And the time is after sunset in the spring and before sunrise in the fall. This occurs when the zodiac lies at a sharp angle relative to the horizon. However, the faintness of the glow means it gets overshadowed. And it gets overshadowed by the brightness of moonlight or light pollution, often making it impossible to detect.

What Causes Zodiacal Light? Let’s Know the Exact Reason!

The zodiacal light emerges due to sunlight reflecting off dust from comets and asteroids that congregates within the plane of the Solar System. The heat from the Sun causes ices laden with dust on comets to vaporize, expanding outward and forming the comet’s coma. Some of this material is push back by the pressure of sunlight, creating a tail that diffuses along the comet’s orbit and enjoying a subsequent existence as the zodiacal light. Additionally, dust resulting from asteroid collisions significantly contributes to this mix. A considerable portion of this dust settles within the Solar System’s plane, scattering sunlight much like the way clouds of dust are stir up by galloping horses.

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Venus and Mars ornament the base of the zodiacal light cone this week. The planets and light cone are centered on the ecliptic which runs through the zodiac constellations Aquarius, Pisces, and Aries in the western sky in February. Source: Stellarium

What is Zodiacal Cloud & How it is Related to Jupiter-Family Comets?

The interplanetary dust within the Solar System collectively shapes a dense cloud resembling a pancake, referred to as the zodiacal cloud. This cloud spans the ecliptic plane. Around 85 percent of this dust originates from sporadic breakups of Jupiter-family comets that are in a state of dormancy. Jupiter-family comets possess orbital periods shorter than 20 years and remain dormant when not actively emitting gases, though they could potentially do so in the future.

The initial comprehensive dynamic model of the zodiacal cloud indicates that the dust must be released into orbits that approach Jupiter in order to create enough disturbance to account for the thickness of the zodiacal dust cloud. Dust particles within meteoroid streams are notably larger, ranging from 300 to 10,000 micrometers in diameter, and they disintegrate over time, transforming into smaller zodiacal dust particles.

What is Poynting-Robertson Effect & How Can it Provides Guidance for its Light?

The Poynting-Robertson effect guides the dust into orbits that are more circular. Though still slightly elongate, causing them to gradually spiral towards the Sun. As a result, a constant influx of fresh particles is necessary to sustain the zodiacal cloud. The cometary dust and dust originating from collisions between asteroids play a significant role in maintaining the dust cloud that generates the zodiacal light.

The size of particles can be reduce through collisions or the process of space weathering. When particles are worn down to dimensions smaller than 10 micro-meters. The pressure exerted by solar radiation propels these grains out of the inner Solar System. Subsequently, the supply of dust is re-fill through the deposition of material from comets.

In 2015, findings from the secondary ion dust spectrometer COSIMA aboard the ESA/Rosetta orbiter affirmed that the likely sources of interplanetary dust are Jupiter-family comets.

How Can You View this Spectacular Sight?

In a dark expanse of sky, the zodiacal light takes on the appearance of a gentle cone or wedge. Its brightness is most visible near the western horizon. And as it ascends, it gradually tapers and fades. You could observe its faintest portions extending to an altitude of at least 45°. Under a truly pristine sky, the zodiacal light doesn’t cease but persists as the even fainter zodiacal band that extends across the eastern sky.

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To see the zodiacal light, find a location with a dark, light-pollution-free sky in the west-southwest direction and look for a tall, Milky Way-like glow above the western horizon at the end of evening twilight. Its tapering form reaches to 45° elevation or higher. Bob King

Solar Spectrum Mirror – A Lens Shaped Region in Space

Zodiacal light emerges as a result of sunlight bouncing off dust particles within the Solar System, which are cosmic dust. As a consequence, its spectrum mirrors that of the solar spectrum. The source of the zodiacal light lies within a lens-shaped region in space, centered around the sun and extending well beyond Earth’s orbit. This substance is refer to as the interplanetary dust cloud. Given that a large portion of this material resides close to the plane of the Solar System, the zodiacal light is visible along the ecliptic.

The quantity of material necessary to generate the observable zodiacal light is rather minimal. If we consider this material in the form of particles measuring 1 mm each. And if each of these particles boasts the same reflecting power (albedo) as Earth’s moon. And the distance between these two is around 8 km.

Zodiacal Light Time – Let’s See it With Human Eye!

When trying to catch a glimpse of the zodiacal light, keep an eye out for something substantial. It spans a significant portion of the celestial realm. The optimal time to witness this phenomenon is as evening twilight draws to a close. During this period, the arch of light reaches its pinnacle, shining most brightly. This brightness persists for a minimum of an hour after twilight concludes. And it gradually fading as it descends towards the western horizon. In this particular season, the planets Venus and Mars will linger near the bottom of the luminous glow. And they are contributing an extra touch of picturesque splendor to the vista.

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Looking for a great photo opportunity with the zodiacal light? On Feb. 20th, the thin crescent Moon will join Venus and Mars, which will be in close conjunction low in the western sky. Source: Stellarium

How to Have All the Prior Knowledge to Observe the Zodiacal Light?

The ethereal zodiacal light, a celestial phenomenon appearing in the western sky, has returned for the month. This ghostly glow emerges after sundown from February 6th to 20th. It is visible around 90 minutes after sunset and lasts about an hour and a half. To witness and photograph this spectacle, find a dark, light-pollution-free spot in the west-southwest direction. Look for a Milky Way-like luminosity above the western horizon with a tapering form reaching at least 45° elevation.

The zodiacal light originates from sunlight reflecting off comet and asteroid dust concentrated in the plane of the Solar System. It takes the shape of a diffuse cone or wedge, brightest near the horizon and fading as it extends higher. Venus and Mars adorn the base of this light cone. It is in the center on the ecliptic side that runs through Aquarius, Pisces, and Aries constellations.

To capture this celestial marvel with your digital camera, use a wide-angle lens and tripod. Switch your camera to manual mode, set the lens aperture wide open (f/2.8 or lower), and focus manually at infinity. Set your ISO to 1600 or 3200, and use exposures of up to 30 seconds. With modern DSLRs, even ISO 6400 can yield noise-free images. This extraordinary event culminates on February 20th. With the thin crescent Moon joining Venus and Mars in close conjunction for a captivating photo opportunity.

view of the gibbous moon
Back of a Canon 5D Mark III showing a live view of the gibbous moon. To set up and focus, I first aimed at the Moon and depressed the live view button, then I pressed the 5x magnify button. Bob King

What Observations has been Made Related to Zodiacal Light?

Over the past few years, various spacecraft observations have unveiled notable patterns within the zodiacal light. These include arrangements like dust bands. They are with remaining from specific asteroid groups, as well as several trails left by comets.

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