Atmosphere

A atmosphere is the thing surrounding a Planet. (It’s air and stuff...) The bigger the atmosphere, the hotter it is. Because when The Suns heat goes into a atmosphere, it gets trapped in it, making the Planet hotter. Earths atmosphere is made of 78% Nitrogen, 21% Oxygen, 0.9 Argon, 0.003 carbon dioxide and 0.097 other. It’s perfect for humans. :)

Venus is hotter than Mercury because Venus has a bigger atmosphere. I might of answered you’re biggest question. Mars has the smallest atmosphere in the solar system. Venus has the largest in the solar system. It’s also sad that humans are ruining Earths atmosphere with smoke and all of that stuff.