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SESK: Stuff Everyone Should Know · sesk.info/astro-venus-runaway-greenhouse

Why is Venus hotter at the surface than Mercury?

Its dense atmosphere drives a runaway greenhouse effect.

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  1. Venus is closest to the Sun
  2. Venus generates heat by fusion
  3. Its atmosphere traps outgoing heat ✔

Why: Venus has a massive carbon dioxide atmosphere that traps heat extremely effectively. Its average surface temperature is about 467 degrees Celsius, even though Mercury orbits closer to the Sun.

Huh, didn't know that: Surface pressure on Venus is about 93 times Earth's sea-level pressure.

The dad joke
Venus never chills because its greenhouse forgot the thermostat.
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References

Answer: Its atmosphere traps outgoing heat. Venus has a massive carbon dioxide atmosphere that traps heat extremely effectively. Its average surface temperature is about 467 degrees Celsius, even though Mercury orbits closer to the Sun.

  1. Venus Facts science.nasa.gov/venus/venus-facts
    Its thick atmosphere traps heat in a runaway greenhouse effect.
    Checked 2026-10-10.

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