Herzberg pointed out direct evidence of H 2 molecules in the atmospheres of the outer planets. The atmospheres of the inner planets and of Saturn 's big moon Titan also show significant CIA in the infrared due to concentrations of nitrogen, oxygen, carbon dioxide and other molecular gases. However, the total CIA contribution of Earth's major gases, N 2 and O 2, to the atmosphere's natural greenhouse effect is relatively minor except near the poles. Extrasolar planets have been discovered with hot atmospheres (a thousand kelvin or more) which otherwise resemble Jupiter's atmosphere (mixtures of mostly H 2 and He) where relatively strong CIA exists.