The first estimate, made in 2003, suggested that the first stars were born as early as a few hundred million years into the history of the Universe. A mere blip in spacetime. Subsequent studies posited 450 million years, and then 550 million years. This latest development puts the halfway point of reionisation around 700 million years, sliding early star-birth a little bit further along down the timeline. The satellite's High-Frequency Instrument, which made this discovery, is the most sensitive to this kind of data.