0.723 A.U. or about 67 million miles. Mass measured by observing the trajectories of spacecraft sent to Venus Surface is relatively smooth with two large areas of uplands, containing mountains comparable in height to those on Earth. Rocky planet, with an iron core.
Surface is no longer active techtonically, although there is evidence of recent volcanic activity.
Thick, dense, pressure about 90 x pressure on Earth. Mostly carbon dioxide, with traces of nitrogen and sulphuric acid. This is a consequence of its orbit being smaller that that of the Earth Earth view only sees top of clouds. Surface mapped out using radar on orbiting Pioneer spacecraft. Venera spacecraft have landed and sent back pictures of surface.