The hottest planet in our solar system is Venus, not Mercury, despite being closer to the sun.

Here's why:

* Venus's thick atmosphere: Venus has a dense atmosphere composed primarily of carbon dioxide, which traps heat through the greenhouse effect. This creates a runaway greenhouse effect, making Venus incredibly hot.

* Surface temperature: The average surface temperature of Venus is a scorching 464°C (867°F). This is hot enough to melt lead!

While Mercury is closer to the Sun, it has a very thin atmosphere, which allows most of the Sun's heat to radiate back into space.