[PapaBear3625]

Perhaps it is because astronomers trained their telescopes at Venus, a planet about the same size as Earth and one that has a very definite greenhouse effect, and the sight made an emotional impression that overbalanced the reason.

Venus' atmosphere is 96% CO2, while Earth has 0.038% CO2. It's a big stretch to think that Earth's CO2 would generate a significant greenhouse effect.

[Vanders9]

Sure, but the principle of global warming is shown in Venus. If you have an atmosphere that is mostly CO2 rather than nitrogen and oxygen, then you do get a greenhouse effect.

Its just that Earth doesnt :)