How do you make a 3D map of the Universe? With a colossal telescope and a five-year mission of course!
The Dark Energy Spectroscopic Instrument (DESI) is on a five-year quest to make the largest-ever 3D map of the Universe.
Though only half-way through its mission, astronomers have used its first year of data to begin answering one of astronomy’s biggest questions: how fast is our Universe expanding?
DESI's mission
DESI has been mounted on the Nicholas U Mayall 4-Meter Telescope at Kitt Peak National Observatory in Arizona since 2021.
It can simultaneously measure the spectra of 5,000 nearby galaxies and distant quasars every 20 minutes, observing a total of 100,000 objects a night.
This allows astronomers to work out the redshift of all the objects observed, or how much their light has been stretched by the Universe’s expansion.
As redshift is closely related to distance, the DESI team can use these to create their 3D map.
From the first year’s data, the team traced out the history of the cosmos’s expansion over the last 11 billion years with a precision better than 1%.
"These first-year data are only the beginning of DESI’s quest to unravel the expansion history of the Universe, and they hint at the extraordinary science to come," says Pat McCarthy, Director of NOIRLab.
