A blanket that will not lift
Why Is Venus Hotter Than Mercury?
Venus is further from the Sun than Mercury but traps heat so well that it ends up far hotter.
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Step 1 of 5
Mercury is the closer planet by a long way.
Mercury orbits nearest the Sun and receives several times the sunlight Venus does, so it ought to be the hotter of the two.
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Step 2 of 5
But Mercury has almost no atmosphere.
With essentially no air, heat absorbed during the long day radiates straight back into space once night falls.
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Step 3 of 5
Venus is wrapped in a crushing thick blanket.
Its atmosphere is overwhelmingly carbon dioxide and presses down about ninety times harder than Earth's, which is like being deep underwater.
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Step 4 of 5
That blanket lets light in but not heat out.
Sunlight passes through and warms the ground, but the heat radiating back is a different kind of light that carbon dioxide absorbs and returns.
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Step 5 of 5
The result is an oven that never cools.
Venus sits around 465°C day and night, hot enough to melt lead, and barely varies between its poles and its equator.
Venus averages about 465°C everywhere, while Mercury swings from 430°C in daylight to −180°C at night.
The short version
Venus is hotter than Mercury because its thick carbon dioxide blanket traps heat, while airless Mercury radiates its warmth straight back to space.
Try it yourself
Compare a car left in the sun with the windows shut against one with them open. The trapped air makes the difference, not the sunlight.
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