1.   In each methane molecule there are four CH bonds.

2.   For example, in the methane molecule there are four CH bonds and thus four bond dissociation enthalpies.

3.   For example, extremely reactive hydroxyl radicals, OH, which are created as ozone encounters other compounds, destroy methane molecules.

4.   The clincher, the astronomers said, was the unmistakeable infrared signature of methane molecules in its atmosphere.