The planet that gives off twice as much heat as it receives from the sun is Venus.

Here's why:

* Dense Atmosphere: Venus has an incredibly dense atmosphere, composed mostly of carbon dioxide, which traps heat through the greenhouse effect.

* Runaway Greenhouse Effect: This dense atmosphere creates a powerful greenhouse effect, leading to extremely high surface temperatures.

* Internal Heat: Venus also has a significant internal heat source from volcanic activity and a possible molten core, contributing to the planet's overall heat output.

While Venus receives less solar energy than Earth, its dense atmosphere and internal heat sources make it significantly hotter.