Some 4 billion years ago, the Sun shone with only about three-quarters the brightness we see today, but its surface roiled with giant eruptions spewing enormous amounts of radiation into space. These powerful solar explosions may have provided the crucial energy needed to create greenhouse gas in Earth’s atmosphere, warming the planet and incubating life.
Nearly four billion years ago, life arose on Earth. Life appeared because our planet had a rocky surface, liquid water, a blanketing atmosphere and a protective magnetic field. A new study of the young, Sun-like star Kappa Ceti shows that a magnetic field plays a key role in making a planet conducive to life.