OPOD - Planetary Quetelet Fringes

Last updated on September 16, 2023

OPOD - Planetary Quetelet Fringes: A Phenomenon of Light and Reflection

When it comes to capturing stunning celestial events, photographers always find innovative ways to showcase the beauty of the cosmos. One such example is Laurent Laveder's remarkable photograph of the March '12 Venus/Jupiter conjunction, where the planets are reflected in a mirror adorned with dew. The result is a mesmerizing display of colored rings, known as "Quetelet fringes" or "rings". These captivating phenomena can be observed not only with planets but also with the sun, moon, lamps, and even on dusty or bedewed windows, mirrors, and still lakes strewn with dust or pollen.

The formation of Quetelet rings and their vibrant colors is attributed to the presence of small micron-sized particles or water droplets resting on or near a reflective surface. In the case of Laurent Laveder's photograph, the incident light from Venus and Jupiter reaches the dewdrops along two routes: directly and after being first reflected from the mirror's surface.

Upon reaching the droplet, the light waves scatter predominantly forwards, creating a series of outgoing spherical waves. These outgoing waves from both routes overlap and combine. In directions where the overlapping wave fronts have the same amplitude and direction (in phase), they reinforce each other, resulting in the presence of light. However, in certain directions, the waves are out of phase and cancel each other out. This cancellation or interference condition is wavelength dependent, giving rise to the beautiful array of colored fringes observed in Quetelet rings.

To delve further into this intriguing phenomenon, let's explore some key aspects:

The Role of Micron-Sized Particles and Water Droplets

• Quetelet fringes occur when small particles or water droplets, typically measuring a few microns in size, are present on or near a reflective surface.
• These particles or droplets act as scattering centers for the incident light, causing it to disperse in various directions.
• The size and distribution of these particles influence the appearance and characteristics of the Quetelet rings, including their colors and intensity.

Reflection and Refraction of Light Waves

• When light encounters a reflective surface, such as a mirror or window, it can be reflected, refracted, or absorbed.
• In the case of Quetelet fringes, the incident light waves can follow two paths: direct transmission through the droplet or reflection from the surface before reaching the droplet.
• The combination of these two paths leads to the interference and overlapping of light waves, giving rise to the formation of the colorful fringes.

Interference and Wavelength Dependency

• The interference of light waves plays a crucial role in the formation of Quetelet fringes.
• When the wave fronts of the scattered light waves overlap and have the same amplitude and direction, they reinforce each other, resulting in constructive interference and the presence of light.
• However, in certain directions, the wave fronts are out of phase, leading to destructive interference and the cancellation of light.
• The wavelength of light determines the specific conditions for constructive and destructive interference, thus influencing the colors observed in the fringes.

Factors Affecting Quetelet Fringe Patterns

• The size, shape, and distribution of particles or droplets on the reflective surface impact the overall appearance and complexity of Quetelet rings.
• Different arrangements and densities of particles can lead to variations in fringe patterns, including their spacing, intensity, and color distribution.
• Environmental factors such as humidity, temperature, and air quality can also influence the formation and visibility of Quetelet fringes.

Other Phenomena Exhibiting Quetelet Fringes

• While Laurent Laveder's photograph beautifully captures Quetelet fringes with Venus and Jupiter as the light sources, these phenomena can be observed with various celestial bodies and artificial light sources.
• The sun, moon, lamps, and even bright stars can create Quetelet rings when their light interacts with particles or droplets near reflective surfaces.
• Dusty or pollen-laden windows, mirrors, and still lakes can also exhibit these colorful fringes under the right conditions.

Appreciating the Beauty of Quetelet Fringes

• Quetelet fringes are not only scientifically fascinating but also visually stunning.
• The delicate rings of vibrant colors add a touch of ethereal beauty to everyday objects and natural landscapes.
• Capturing these phenomena through photography allows us to witness and appreciate the wonders of light, reflection, and interference in our surroundings.

In conclusion, Quetelet fringes, or rings, are a captivating phenomenon resulting from the interaction of light with micron-sized particles or water droplets on or near reflective surfaces. Whether observed with planets, the sun, moon, lamps, or even on dusty windows and still lakes, these colorful fringes offer a glimpse into the intricate workings of light waves and their interference patterns. Laurent Laveder's photograph serves as a testament to the endless possibilities for creative exploration in atmospheric optics and reminds us of the profound beauty that surrounds us in the natural world.

Dew, Mirrors & Planets

The Internet is awash with images of the March '12 Venus/Jupiter conjunction - but none like this!

Laurent Laveder (Pixheaven, Photoghraphe) pictured the planets reflected in a mirror. The mirror had dew. The result, an exquisite set of coloured rings passing across Venus & Jupiter.

These are �Qu�telet fringes or rings�.

They do not need a planet, the sun, moon or a lamp will do. They can be found on dusty or bedewed windows and mirrors. Dusty or pollen strewn still lakes also show them.

Image ©Laurent Laveder, shown with permission.

Quételet rings and colours are generated when small micron-sized particles or water drops rest on or are close to a reflecting surface.

Light, in this case from Venus and Jupiter, reaches the drop along two routes, (A) directly and (B) after being first reflected from the surface.

The drop scatters the incident light waves predominantly forwards into a series of outgoing spherical waves. The two sets of outgoing waves overlap and combine.

In directions where the overlapping wave fronts have the same amplitude direction (in phase) they reinforce and there is light. In some other directions the waves are out of phase and they cancel each other out. The cancellation or interference condition is wavelength dependent and so the resultant fringes are coloured.

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Reference Atmospheric Optics

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