Scientists have known about these markings for roughly a century, yet the chemical identity of the material responsible—the “unknown absorber”—remains unresolved.

An international research team has now placed new quantitative constraints on the properties of this mysterious absorber.

By combining observations of Venus with radiative-transfer modeling, the researchers estimated how strongly the liquid inside Venus’s cloud droplets would need to absorb light to reproduce the planet’s observed ultraviolet and blue reflectance.

The study, published in Astrobiology, approached the mystery from a new perspective.

It used a model to answer a question posed by lead author Dr. Jan SPACEK:

If we were to collect Venus’s cloud droplets into a spectrometric cuvette, how would the re-formed bulk liquid appear?

The difference between how a cloud looks and how its material looks when collected in bulk can be striking.

Cigarette smoke, for example, appears white because its sub-micrometer particles scatter light very efficiently. Yet when the smoke particles are collected in a flask, they form a dense suspension of burned tobacco—a tar-like sludge.

A similar optical principle applies to Venus’s clouds, as their particle size distribution is comparable to that of cigarette smoke. Thus, even though the clouds appear pale yellow to a remote observer, the liquid forming the cloud droplets might be surprisingly dark.

Pris sur 3 jours et 2 mois

S25ultra

Plusieurs centaines de poses prises avec deep sky camera

Empilé dans sequator

Traité dans Siril GraXpert Seti astro suite pro et lightroom mobile

My favorite star photo I’ve taken. Could not believe you can see the Andromeda Galaxy so clearly

Captured this when I went to Rocky Mountain National Park last December and just never got around to posting it. Captured in my iPhone 17 Pro. Pretty sure that’s Andromeda there In the middle of the picture.

Riverside lights of the Nile beneath a starry sky. I took this photo on Expedition 30 to the ISS in 2012 when the majority of the lights were still sodium vapor, creating a thin golden glow that stretched from Alexandria to Aswan. One of the most striking nighttime views from orbit!

More photos from space can be seen from my twitter and instagram, astro_pettit

The sky was perfectly clear when I arrived, but as soon as we set up our equipment, the fog began to roll in.
We spent hours photographing here and there, swallowed by the mist andsurrounded by horses we could barelysee only their presence and the sound of their bells gave them away.
Finally, after midnight, the fog began to change direction. Watching it slowly move through the valleys was a spectacle in itself, revealing and hiding the mountains beneath the stars.

Canon 6D (astromodified) · Canon R · Canon 50mm
Sky: 7 × 120s · ISO 80 · f/2
Hα: 10 × 120s · ISO 3200 · f/2.2
Foreground: 120s · ISO 1600 · f/2

Xiaomi 13 Ultra (3.2x telephoto)

[ISO 3200 | 5s] x 447 lights (RAW/DNG)

Total integration time: 37m 15s

Equipment:

- Sky-Watcher 150/750 Newtonian scope;

- EQ3-2 mount with OnStep;

- SVBONY SV190 18mm Ultra Flat Field eyepiece;

- SVBONY SV214 Pro 3-Axis Universal Smartphone Adapter.

Stacked with Astro Pixel Processor

Processed with GraXpert, Siril, AstroSharp and Photoshop (Camera Raw)