About:

• At about 4.6 billion years of age, the sun is middle aged, that is, it will continue to live for roughly the same period. There are accurate methods for estimating the age of the Sun, such as by using radioactive dating of very old meteorites that have fallen on the Earth.
  
  
• However, for more distant stars which are similar in mass and age to the Sun, such methods are not possible.
  
  
• One of the methods used is called gyrochronology. There is a relationship between rotation rate and age, that is the rotation rate of a star slows down with age.
  
  
• However, there is a breakdown of the gyrochronology relationship, because after midlife, a star's rate of spin does not slow down with age as fast as it was slowing down earlier.
  
  
• Another intriguing fact is that the Sun’s activity level has been observed to be much lower than other stars of similar age.
  
  
• A third observation that is part of the puzzle is that there have also been periods in the past when extremely few sunspots were observed on the Sun for several years at a stretch. For instance, during the Maunder minimum which lasted from 1645 to 1715.