OPOD - Venus Optics

Last updated on September 16, 2023

OPOD - Venus Optics: Unveiling the Elongated Venus Corona

Have you ever wondered why the coronae of Venus and Jupiter appear elongated instead of the typical circular shape? It turns out that this phenomenon is not exclusive to spherical objects. Even non-spherical entities like oriented pollen grains and pond algae can produce asymmetric coronae elongated perpendicular to the direction of their longer axes.

The surprising aspect of this discovery is that Venus and Jupiter, celestial bodies that we often associate with perfection and symmetry, exhibit these elongated coronae. It is important to note that the phase of Venus does not play a role in producing this effect. So, what could be the cause?

Researchers believe that the elongated coronae observed around Venus and Jupiter are a result of light diffracted by small ice crystals present in the clouds. These ice crystals, with sizes of approximately 0.3mm, have the ability to create coronae up to 0.2° in length. It is hypothesized that column crystals of this size are large enough to align themselves aerodynamically, with their long axis positioned horizontally. As a result, when Venus is relatively low in the sky, it produces a vertically elongated corona.

To further understand this phenomenon, let's delve into the characteristics of ice crystals and their behavior within the atmosphere:

1. Ice crystals: These tiny particles are formed when water vapor freezes onto surfaces such as dust particles or existing ice nuclei. They can vary in shape and size, ranging from simple hexagonal plates to more complex columnar or dendritic structures.

2. Aerodynamic orientation: In certain atmospheric conditions, ice crystals can align themselves in a preferred orientation due to air currents and turbulence. This alignment allows them to present a larger surface area perpendicular to the direction of airflow, enhancing their aerodynamic stability.

3. Diffracted light: When light encounters an obstacle or passes through a medium with varying refractive indices, it undergoes diffraction, resulting in the bending or spreading of light waves. In the case of Venus, the diffracted light by the ice crystals in its surrounding clouds contributes to the elongated corona effect.

4. Cloud composition: Clouds are composed of a combination of water droplets and ice crystals. While water droplets mainly contribute to the formation of circular coronae, the presence of ice crystals can introduce asymmetry and elongation to the corona shape.

Now that we have explored the scientific aspects of Venus optics, let's take a moment to appreciate the beauty and complexity of these elongated coronae. The images captured by Alexandra Farkas on November 24th in Mogyoród, Hungary, provide a stunning visual representation of this phenomenon.

It is important to mention that this article has been automatically converted from the old site and may not appear as intended. However, you can still find the original article here for further reference.

In conclusion, the discovery of elongated coronae around Venus and Jupiter challenges our conventional understanding of optical phenomena. By studying the behavior of ice crystals in the atmosphere and their interaction with light, scientists have shed light on this intriguing phenomenon. So, the next time you gaze at the night sky and witness an elongated Venus corona, remember that there is a fascinating scientific explanation behind its mesmerizing appearance.

Elongated Venus Corona ~ Pictured by Alexandra Farkas 24th November at Mogyoród, Hungary. ©Alexandra Farkas, shown with permission.

We see non circular coronae from oriented pollen grains and even pond algae. Both objects are non spherical and produce asymmetric coronae elongated perpendicular to the direction of their longer axes.

That Venus and Jupiter show them is a surprise. The phase of Venus does not produce the effect. It is likely that the coronae are produced by light diffracted by small ice crystals in clouds. Alexandra's corona or aureole is ~0.2° long. Crystals of size ~0.3mm would produce it. Column crystals of that size are large enough to be aerodynamically oriented with their long axis horizontal to give a vertically elongated Venus corona when reasonably low in the sky.

Note: this article has been automatically converted from the old site and may not appear as intended. You can find the original article here.

Reference Atmospheric Optics

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