text: All of the terrestrial planets have at one time or another had volcanoes and it is also believed that the moon may once have been volcanically active.  However Mercury, Mars and the moon have long gone cold (at least we believe so) inside and are no longer volcanically active.  \nThe Jovian moon Io is volcanically active and it also has a rocky surface.  If one supposes that any body that has had a period of liquefied mantle, then the heavier elements like Iron would settle into the core which means that all of the Terrestrial planets and many of the larger moons of Jupiter possibly even Titan and Triton may have iron cores.\nAs for Titan and Triton, geothermal activity has been seen on Triton in the form of geysers, but no recent evidence of volcanic (liquefied rock) activity.  And since Titan is covered with clouds, no one can really say about it.\nVenus is still hot enough inside to have some geothermal eruptions, but, again, due to the cloud cover, we have not detected any.