Solar flares could have aided development of life on Earth

Science News : Astronomers study young Sun-like stars to learn what our solar system might have been like early in Earth’s existence. According to Vladimir Airapetian of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and his colleagues, those stars are significantly more active than the present Sun. The researchers estimate that 4 billion years ago Earth could have been struck by large solar flares at least once per day. If that’s true, then the radiation could have triggered chemical reactions that produced nitrous oxide, a greenhouse gas, and hydrogen cyanide, a building block of DNA. That could help explain the development of life on Earth, the earliest traces of which are around 4 billion years old. At that time, the Sun had 70–75% of its current brightness, so the presence of greenhouse gases was necessary to keep temperatures on Earth above freezing.