After years of meticulous planning, the European Space Agency launched the Euclid satellite in early July 2023, embarking on a six‑year journey to illuminate the unseen components that dominate our cosmos.
Current cosmological models cannot fully explain the universe’s rapid expansion and intricate geometry without invoking vast amounts of invisible energy and mass—collectively known as dark energy and dark matter. These enigmatic entities shape the observable universe, yet they neither emit nor reflect light, making them notoriously difficult to study. Euclid’s primary goal is to decipher this dark sector by mapping its influence through the visible universe.
The mission is a collaborative effort involving Canadian partners such as the University of Waterloo, the University of British Columbia, the National Research Council of Canada, the Canada‑France‑Hawaii Telescope, and the Canadian Space Agency. Together they are charting more than one‑third of the sky beyond the Milky Way, capturing images of billions of galaxies up to ten billion light‑years away. This will be the most comprehensive extragalactic map ever produced.
Euclid’s 1.2‑meter telescope, coupled with a 600‑megapixel camera, delivers images at least four times sharper than ground‑based observations. By measuring redshift—the shift in a galaxy’s light caused by cosmic expansion—scientists can estimate distances and transform two‑dimensional images into a three‑dimensional map of the cosmos.
While the satellite’s primary images are black and white, an international network of ground‑based observatories will supply color data across the visible spectrum. Canadian researchers will play a pivotal role in this effort, bridging the data gap with additional filters. In addition, a 65‑megapixel camera and spectrophotometer aboard Euclid will observe near‑infrared light through three filters, refining distance calculations.
To probe the distribution of dark matter, the team will exploit gravitational lensing—where foreground mass bends the light of background galaxies. By quantifying this distortion and analyzing galaxy clustering, scientists will reconstruct the dark universe’s structure.
“Euclid was designed to unlock the mysteries of the dark universe, but in doing so it also gathers unprecedented data on the bright universe,” said Douglas Scott, Professor of Physics and Astronomy at UBC, in a press release. “This dual focus means we will uncover discoveries beyond our initial expectations. That is the most exciting aspect of Euclid.”
