Clouds or haze on planet Venus! Take a look at the image. These unusual clouds/haze were discovered last July by ESA's robotic Venus Express spacecraft currently orbiting Venus. The bright and smooth haze was found by Venus Express to be rich in sulfuric acid, created when an unknown process lifted water vapor and sulphur dioxide from lower levels into Venus' upper atmosphere.
Last July, these smooth acidic clouds spread from the South Pole of Venus across half the planet. The cause of the dark streaks in the clouds is also not yet understood and is being researched.
The above false-color picture of Venus was taken last July 23rd in ultraviolet light. It shows the unusual haze as relatively smooth regions across the image bottom. NASA