Our Universe is undergoing an accelerated expansion. Since matter gravitates, cosmic expansion would slow down in a matter-dominated universe. Thus the unknown nature of the observed cosmic acceleration has been dubbed “dark energy”. Euclid will map the large-scale structure of the Universe over ~15,000 square degrees, nearly half of the full sky excluding the regions dominated by the stars in our Milky Way galaxy. It will measure galaxies out to distances which corresponds to a look-back time of ~10 billion years, covering the period over which dark energy accelerated the expansion of the Universe.

All Euclid data will be made public in three major data releases (DR1, DR2, DR3), phased with the survey progress, with the final DR3 a year after the end of the main survey. Preceding each major DR are “quick releases” (Q1, Q2, Q3, Q4) of selected areas and data-products, to demonstrate the data to be expected, and to allow scientists to sharpen their data analysis tools. Well-characterized and validated data will be released via ESA’s Euclid Science Archive System, and by the NASA/IPAC Infrared Science Archive.