This is indeed a very interesting article, and is of personal interest to me.
The visibility of white spots and terminator anomalies on Venus have been observed almost back to the invention of the telescope in the 1840s.
Those interested might like to read a bit on the history of visual observations of Venus and the held belief in possibility of very high mountains. This is discussed in an article that once feature in the RASNZ journal "
Southern Stars" in 2003. This is an article "
Johann Schröter, William Herschel and the Mountains of Venus: Overview." at
http://homepage.mac.com/andjames/PageVenus005.htm
As for this truly being caused by volcanism is very unlikely. At the latitude of the spot, there are mostly highlands. The highest mountain is about six or seven kilometres and is located on the
Ishtar Plateau. However the size of the volcano to disturb the atmosphere this much would far exceed any that exist on the Earth, and considering the viscose nature of the atmosphere. To change it that much would take an incredible amount of energy to leave a mark this size. In probability, it would likely be some kind of upper atmospheric effect.
All so the 4 days quoted is interesting, as this is the circulation rate of Venus' atmosphere already confirmed by visual and satellite observations around the planet.
I've have seen spots like his one several occasions doing dichotomy of Venus observations years ago. They are not too rare, but no one as far as I know have had this confirmed by direct observation. needless to say, the Venus Express image is not visual but is in the ultra-violet. Visually, white spots are normally rather subtle - but at least reproducible and visible to multiple observers without doubt.
Be good to see where how long this effect lasts, as it might tell us more about the atmospheric of this somewhat bizarre planet.
Venus Atmosphere and Unlikely Volcanos
