A surprising chill before the cosmic dawn

An experiment to estimate when stars began to form in the Universe suggests that gas temperatures just before stars appeared had fallen well below predicted limits, and that dark matter is not as shadowy as was thought._ Nature 555, 38-39 (2018)

ESA’s Star Mapper visualisation

In 1989, ESA launched the first space mission dedicated to astrometry – the science of charting the sky. The satellite was named Hipparcos, echoing the name of ancient Greek astronomer, Hipparchus, who compiled the oldest known stellar catalogue in the second century BC. _ESA