The Universe still has plenty of hydrogen, but its ability to turn that fuel into new stars appears to be fading.

The Universe is producing far fewer new stars than it did billions of years ago. Over the past 4.5 billion years, the cosmic star formation rate has fallen to less than half its former level. Yet one of the most important ingredients needed to make stars has declined only modestly.

An international team led by researchers from the Chinese Academy of Sciences (CAS), working with the Dark Energy Spectroscopic Instrument (DESI) project, reached this conclusion after studying the evolution of neutral atomic hydrogen across the Universe. The researchers used China’s Five-hundred-meter Aperture Spherical radio Telescope (FAST) to make exceptionally precise measurements spanning the past 4.5 billion years.