Volcanology of Venus
The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System. It has a surface that is 90% basalt, and about 65% of the planet consists of a mosaic of volcanic lava plains, indicating that volcanism played a major role in shaping its surface. There are more than 1,000 volcanic structures and possible periodic resurfacing of Venus by floods of lava. The planet may have had a major global resurfacing event about 500 million years ago, from what scientists can tell from the density of impact craters on the surface. Venus has an atmosphere rich in carbon dioxide, with a density that is 90 times greater than Earth's atmosphere.
Atmosphere of Venus
It has been proposed that microbes at this level could be soaking up ultraviolet light from the Sun as a source of energy, which could be a possible explanation for dark patches seen on UV images of the planet. Large, non-spherical cloud particles have also been detected in the cloud decks. In 2012, the abundance and vertical distribution of these unknown ultraviolet absorbers in the Venusian atmosphere have been investigated from analysis of Venus Monitoring Camera images, but their composition is still unknown. In 2016, disulfur dioxide was identified as a possible candidate for causing the so far unknown UV absorption of the Venusian atmosphere.