Stars similar to our Sun — “solar proxies” — enable scientists to look through a window in time to see the harsh conditions prevailing in the early or future Solar System, as well as in planetary systems around other stars. These studies could lead to profound insights into the origin of life on Earth and reveal how likely (or unlikely) the rise of life is elsewhere in the cosmos. This work has revealed that the Sun rotated more than ten times faster in its youth (over four billion years ago) than today generating a stronger magnetic field and stronger activity. This also meant that the young Sun emitted X-rays and ultraviolet radiation up to several hundred times stronger than the Sun does today.
Credit: IAU/E. Guinan