01
Venus's thick CO₂ blanket
Venus's atmosphere is about 96% carbon dioxide and 90× thicker than Earth's, trapping heat in a runaway greenhouse effect.
Solar system · Question
Why is Venus hotter than Mercury?
Mercury is the closest planet to the Sun. Venus is the second closest — and yet Venus is the hottest planet in the solar system, hotter than Mercury by over 250°C. Distance from the Sun isn't the whole story.
Visual model
Average temperature, all eight planets.
NASA mean-temperature figures: Venus (+464°C) is 297°C warmer than Mercury (+167°C).
Compare the NASA figures below. Positive values sit to the right of zero; negative values to the left.
Each horizontal bar uses the same linear Celsius axis (−250°C to +500°C). 0°C is the vertical reference line. The values are NASA illustrative planetary means, not live weather.
Evidence comparison / NASA
The hotter world is farther from the Sun.
Test the distance-only explanation against NASA's published temperatures. Mercury's extreme local day and night values are not global means; Venus's 464°C is a global mean.
−200°C0°C+200°C+500°C
Mercury
−180+430
Extrema and meanVenus
Mean +464°C
Venus: +464°C mean / Mercury: +167°C mean. Venus averages 297°C hotter even though Mercury receives more direct sunlight. A dense CO₂ atmosphere is the essential difference.
Temperature range is drawn on the same linear Celsius axis. Mercury's −180°C night minimum and +430°C day maximum are local extrema; its +167°C and Venus's +464°C are NASA illustrative global means. No invented hour-by-hour temperatures. Sources: NASA Mercury Facts · NASA Solar System Temperatures.
What kind of temperature is each figure?
The NASA comparison is not a set of eight comparable solid-surface measurements. Mercury, Venus, Earth and Mars use averages over rocky surfaces; Jupiter, Saturn, Uranus and Neptune have no solid landing surface, so their values refer to approximately Earth's sea-level pressure (1 bar) in the atmosphere. Mercury's mean hides extreme day–night variation.
| Planet | NASA mean | Measurement reference |
|---|---|---|
| Mercury | +167°C | Rocky surface, global mean |
| Venus | +464°C | Rocky surface, global mean |
| Earth | +15°C | Rocky surface, global mean |
| Mars | −65°C | Rocky surface, global mean |
| Jupiter | −110°C | Atmosphere at ~1 bar |
| Saturn | −140°C | Atmosphere at ~1 bar |
| Uranus | −195°C | Atmosphere at ~1 bar |
| Neptune | −200°C | Atmosphere at ~1 bar |
References: NASA Solar System Temperatures and NASA Planetary Fact Sheet Notes. The pressure reference and global averages are not identical measurement environments.
What's simplified
Distance isn't the deciding factor. Atmosphere is.
02
Mercury has almost none
Mercury has essentially no atmosphere to trap heat, so its dayside bakes while its nightside can drop to -180°C — the "average" hides an enormous swing.
03
These are averages
A single number can't show day/night or pole/equator swings, which are extreme on airless worlds like Mercury and the Moon.
Misconception check
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Go deeper
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Next in this series →
Orbital periods ↗
Calculate your age on Mars or Jupiter.
Gravity
Weight on other planets
Another way a planet's numbers surprise you.
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