Venus's internal structure. Computer artwork showing the core ( bronze, centre), mantle (orange) and crust (light orange-yellow) of Venus. At the centre of Venus is a primarily solid iron core, which underlies a thick mantle made mainly of silicate minerals. On top of this is a very thin crust, which is only around 30 kilometres thick (compared to a maximum of around 70 kilometres for Earth's crust). Venus also has a thick, acidic atmosphere, which traps the heat of the Sun (a runaway green house effect). This makes Venus the hottest planet in the solar system, with surface temperatures reaching over 400 degrees Celsius.