No shortage of mysteries on Venus   The volcano, Sif Mons, on Venus shows evidence for past activity in the form of a solidified lava flow that shows up in this image as a brighter streak down the sides of its cone. Planetary scientists would like to know if such eruptions are taking place today. This 3-D view of the surface of Venus was produced in a computer using radar data collected by NASA's Magellan spaceprobe from orbit, in the early 1990s.   This is a NASA/ESA Hubble Space Telescope ultraviolet image of the planet Venus, taken on 24 January 1995, when Venus was at a distance of 113.6 million kilometres from the Earth.   Golubkina crater on Venus is 34 kilometres in diameter. Studying the number and size of craters on Venus proves that the surface of the planet is only 500 million years old. Scientists believe that some kind of volcanic catastrophe, 500 million years ago, spilled molten lava across the entire surface of the planet destroying all the older craters. Release date: 18 August 2005