Jupiter is actually not the hottest planet in our solar system. That title belongs to Venus, which has an average surface temperature of around 464°C (867°F).

Here's why Venus is so hot:

* Runaway Greenhouse Effect: Venus has a very dense atmosphere composed primarily of carbon dioxide, which acts like a blanket, trapping heat from the sun. This creates a powerful greenhouse effect, causing the planet's surface to heat up tremendously.

* Slow Rotation: Venus rotates incredibly slowly, taking about 243 Earth days to complete one rotation. This slow rotation prevents heat from being distributed evenly across the planet.

Jupiter, on the other hand, is a gas giant with a much thinner atmosphere compared to Venus. It does have internal heat sources from gravitational pressure and core formation, but it doesn't experience the same runaway greenhouse effect. Jupiter's upper atmosphere is actually very cold, reaching temperatures as low as -145°C (-234°F).

While Jupiter's internal heat source is significant, its immense size and distance from the sun mean that its overall temperature is still much lower than Venus.