Euclid

Key facts

Mission & specifications

Mission

Euclid is a European Space Agency telescope built to confront the deepest mystery in cosmology: why the expansion of the universe is speeding up. About 95 percent of the cosmos appears to be made of invisible dark matter and a still-stranger dark energy, neither of which has ever been directly seen. Launched on 1 July 2023 to the Sun–Earth L2 point, Euclid attacks the problem by surveying more than a third of the entire sky, charting the shapes, positions and distances of billions of galaxies across ten billion years of cosmic history. Its 1.2-metre telescope feeds a visible-light camera and a near-infrared instrument that together measure two subtle signatures: the way the images of distant galaxies are faintly sheared by the gravity of intervening dark matter — an effect called weak gravitational lensing — and the rippled, large-scale pattern in how galaxies cluster, which acts as a cosmic ruler. By watching how those patterns have grown over time, cosmologists can test whether dark energy is truly Einstein's constant or something that changes. Euclid's first images, released in late 2023, showed both pin-sharp detail and an enormous field of view, and its six-year survey is building the largest, most precise three-dimensional map of the universe ever made — a single observation set that thousands of astronomers will mine for decades.

1. 2023Launch on a Falcon 9Launch

   Euclid sets off for the Sun–Earth L2 point to begin its survey of the dark universe.

2. 2023Arrival at L2Arrival

   The telescope settles into its halo orbit 1.5 million km from Earth and begins commissioning.

3. 2023First survey images releasedMilestone

   Early images show pin-sharp detail across an enormous field of view, proving the instruments.

4. 2024Routine survey beginsMilestone

   Euclid starts the six-year campaign to map billions of galaxies over a third of the sky.

Images

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