Venus is so hot primarily because it has a very thick atmosphere composed mainly of carbon dioxide, which creates an intense greenhouse effect. This atmosphere traps heat from the Sun, preventing it from escaping back into space, causing surface temperatures to soar to about 465 degrees Celsius (870 degrees Fahrenheit), hotter even than Mercury, the planet closest to the Sun.
Thick Carbon Dioxide Atmosphere
Venus's atmosphere is about 100 times denser than Earth's and is mostly carbon dioxide, a potent greenhouse gas. This dense concentration makes the atmosphere extremely effective at absorbing and trapping infrared heat radiated from the planet's surface.
Runaway Greenhouse Effect
Venus experiences a runaway greenhouse effect where the heat trapped amplifies further heating. Early in its history, Venus may have had water that evaporated, adding water vapor (another greenhouse gas) to the atmosphere, intensifying the heating until surface temperatures reached extreme levels.
Proximity to the Sun
Being closer to the Sun than Earth also contributes to Venus's heat, but it is primarily the greenhouse effect that makes it hotter than even Mercury, which has a very thin atmosphere and can lose heat quickly at night despite being closer to the Sun.
In summary, Venus's extreme heat is due to its thick, carbon dioxide-rich atmosphere causing a strong greenhouse effect that traps solar heat, creating surface temperatures high enough to melt lead.
