Identifying the mysterious dark bands in Venus’s atmosphere

Scroll down to read this post.
For many reasons, mostly political but partly ethical, I do not use Google, Facebook, Twitter. They practice corrupt business policies, while targeting conservative websites for censoring, facts repeatedly confirmed by news stories and by my sense that Facebook has taken action to prevent my readers from recommending Behind the Black to their friends.
Thus, I must have your direct support to keep this webpage alive. Not only does the money pay the bills, it gives me the freedom to speak honestly about science and culture, instead of being forced to write it as others demand.


Please consider donating by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below.


Regular readers can support Behind The Black with a contribution via paypal:

Or with a subscription with regular donations from your Paypal or credit card account:

If Paypal doesn't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652


You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.

The uncertainty of science: Scientists have now proposed two new best candidates for the unknown major component in Venus’s upper atmosphere that was first identified in 1974 when Mariner 10 took the first good close-up images.

We have analyzed spectra taken during the second Venus flyby of MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft on its route to Mercury, in 2007. Using a numerical code, we have reproduced the light reflected by the equatorial atmosphere of the planet and retrieved the distribution of particles in the upper atmosphere of Venus, with a cloud top of some 75 km above the surface. We have also retrieved the absorption spectrum of the puzzling absorber and compared it with some previously proposed candidates. While no perfect match is found, sulfur-bearing species (S2O and S2O2) provide the best agreement. There is still a long way to undoubtedly identify Venus’s UV absorber, but this work provides substantial spectral constraints.

The dark absorber shows up as dark streaks in the upper atmosphere, and allows images to track wind and cloud movement. No one has been able to firmly identify it.

S2O and S2O2 are disulfur monoxide and disulfur dioxide respectively, both of which are unstable on Earth. The first is thought to have been detected in Io’s numerous volcanic eruptions, with it settling as a solid around at least one volcano, Pele. The second has already been suggested as the dark absorber. This research helps confirm that earlier research.

Note however that other research says there is too little sulfur in Venus’s atmosphere for this to be its dark absorber. The science here therefore remains decidedly unsettled.


Leave a Reply

Your email address will not be published. Required fields are marked *