Cosmoview Episode 78: DESI Looks 11 Billion Years Into the Past to Reveal Most Detailed View Ever of the Expanding Universe

Since beginning its survey of the sky in 2021 the Dark Energy Spectroscopic Instrument (DESI) has observed a new set of 5000 galaxies every 20 minutes, totalling more than 100,000 galaxies per night, in its quest to create the largest 3D map of the Universe ever. Using the survey’s first-year data, which contains the largest extragalactic spectroscopic sample ever collected, astronomers report that they have measured the Universe’s expansion history over the last 11 billion years with a precision better than 1%. These measurements confirm the basics of our best model of the Universe, while also uncovering some tantalizing areas to explore with more data.