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By Cheryl Kahla

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PHOTO: One image, a billion galaxies! This is the largest map of the universe to date

See this image below? Now prepare to have your mind blown... This is the largest 2D skymap of the universe today: a single image revealing more than a billion galaxies.

More than a billion galaxies can be seen in the latest (and largest) map of the universe, thanks to the scientific data released by the Dark Energy Spectroscopic Instrument (Desi) Legacy Imaging Survey.

The survey, which aims to better understand dark energy, aggregates data from telescopes around the world to create a massive map of the sky.

Pictured: A billion galaxies

The most recent space data set (the tenth survey from Desi) contains images taken in additional colour filters, including infrared light data to help calculate the redshifts of distant galaxies.

WATCH: Making the largest universe map

National Science Foundation astronomer Alfredo Zenteno said the near-infrared wavelength data allows the research team “to better calculate the amount of time it took light from those galaxies to reach Earth.” [1]

In addition, Mara Salvato, a researcher at the Max Planck Institute for Extraterrestrial Physics said these calculations are “essential to identifying the origin of the emission.”

These origins could include clusters of galaxies and active supermassive black holes, Salvato said.

Understanding the universe

The Desi project is currently conducting a spectroscopic survey of 40 million galaxies selected from the billion-plus imaged by the legacy survey.

The Dark Energy Spectroscopic Instrument (DESI)
The Dark Energy Spectroscopic Instrument (DESI) at the Kitt Peak National Observatory near Tucson, Arizona. Photo: NOIRLab/KPNO/NSF/AURA/P. Marenfeld

This work is vital to understanding cosmic origins and the evolution of matter and energy. And the only way to do that is to map how the universe expanded over the past 12 billion years.[2]

In order to compile such a massive data set, the survey collects data from telescopes and feeds it to through a series of supercomputers to generate the map as seen above.

One such telescope is situated at the Kitt Peak National Observatory in Arizona, United States, while a second one is at the Cerro Tololo Observatory in Chile, South America.

Data for days (and light years)

The project has been ongoing for the past six years and involves three telescopes, one petabyte of data, and 100 million CPU hours on the world’s most powerful computers.

Part of the largest map of the universe, showcasing more than a billion galaxies
This is an image centered on a relatively nearby galaxy cluster dubbed Abell 3158. Light from these galaxies had a redshift value of 0.059, meaning that it traveled approximately 825 million years on its journey to Earth. Photo: DESI Legacy Imaging Survey/NOIRLab/NSF/AURA

Just FYI: One petabyte is 1 000 terabytes, or 1 000 000 gigabytes. To stream one Netflix episode averages out at around 500 megabytes, right?

So 1 million gigabytes would roughly equate to 2 million 40-minute Netflix episodes. Wild.

Here’s a different perspective: some estimates suggest a petabyte is the equivalent of 20 million tall filing cabinets or 500 billion pages of standard printed text.

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[1] Over One Billion Galaxies Blaze Bright in Colossal Map of the Sky; Charles Blue; NoirLab; 23 February 2023
[2] The Evolution of the Universe; P. James E. Peebles, David N. Schramm, Edwin L. Turner, Richard G. Kron, Scientific American; 1 October 1994

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Data Science Space (Astronomy)

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