https://thenextweb.com/syndication/2020/05/02/the-sun-is-less-active-than-sibling-stars-suggesting-its-entering-old-age/

All stars emit varying amounts of light over time – and the Sun is no exception. Such changes in starlight can help us understand how habitable any planets around other stars are – a very active star may bombard its planets with harmful radiation. Now a new study, published in Science, shows that the Sun is significantly less active than other, similar stars.

In many stars, the observed variation in brightness is driven by their internal magnetic field. When parts of the magnetic field breaks out through a star’s surface, it can cause dark regions known as starspots or brighter regions (known as faculae) in the star’s atmosphere. As a star rotates on its axis, so the bright and dark regions pass across the face of the star from our viewpoint, causing a periodic change in brightness of the star as a result.