The iron level of the universe increases with time as successive generations of stars form and die. We can use the iron abundance of a star as a qualitative “clock” telling us when the star was formed.

In the case of the star we have announced, the amount of iron present is less than one millionth that of the Sun, and a factor of at least 60 times less than any other star. This indicates that our star is the most ancient yet found.

Stars are like time capsules, they lock away a sample of gas from which they form. In the case of the star we have discovered, this has enabled us to study in detail a sample of gas from approximately 13.6 billion years ago.

This is so long ago that the star predates the formation of the Milky Way. It likely formed in a small cloud of gas and eventually many of such clouds fell together under gravity to form the grand spiral galaxy we call home.

This star has born silent witness to 99% of the life of the universe – it has spun impervious, slowly converting hydrogen into helium as demanded by gravity.