September 2012: The sulphur dioxide concentration in the Venusian atmosphere has been observed to vary both across the planet, being greatest near the equator, and also globally in a long-term way, for reasons not yet known, according to results presented at this year's European Planetary Science congress in Madrid. A short interview with planetary scientist Emmanuel Marcq is available here.

It would be interesting to see if these variations coud be in any way correlated with observations from the Earth. The sulphur dioxide concentration affects UV reflectivity of the top of the atmosphere, according to Marcq.