Sun was 30% dimmer 3 billion yrs ago, Earth warmed by nitrous oxide: NASA study

A study conducted by NASA scientist Vladimir Airapetian revealed the sun was 30% less bright around three billion years ago, which could have frozen Earth. However, superflares from the young sun may have led to nitrous oxide production, a greenhouse gas 300-times more potent than carbon dioxide, on Earth. This may have helped Earth hold onto heat, the study added.