The European Space Agency’s (ESA) Euclid flagship Dark Energy Satellite Mission has launched from Cape Canaveral in Florida on a SpaceX Falcon 9 rocket.

Euclid’s 6-year mission is to map the dark Universe, using the positions of galaxies and images of dark matter produced from the gravitational lensing distortions of distant galaxies. The galaxy and dark matter maps contain information about the expansion history of the Universe and the growth of structure within it. By analysing these maps, astronomers will be able to determine the nature of both dark matter and dark energy. Dark matter, which unlike normal matter does not reflect or emit light, binds together galaxies creating the environment for stars, planets and life, while dark energy is the mysterious new phenomenon which is pushing galaxies away from each other and causing the expansion of the Universe to accelerate.

To achieve this, the Euclid Consortium team will carry out a very precise and accurate analysis of the images and distances of 1.5 billion galaxies over one-third of the sky. Gravitational lensing causes a one part in a hundred change in these galaxy images, which need to be measured from the sample to a precision of one part in a hundred thousand, presenting a major data-analysis challenge. Euclid will also measure the spectrum of light from over 35 million galaxies to accurately measure their distance from Earth.

To carry this out the Euclid satellite hosts two state-of-the-art instruments, an optical camera (VIS) built in the UK, and a Near-Infrared (NISP) camera led by France. The VIS Instrument will take images as sharp as those from the Hubble Space Telescope to measure the gravitational lensing distortions. The NISP Instrument will take multicolour images and the spectrum of light of galaxies from which their distance can be measured. Euclid’s wide field of view and large instruments will allow it to image more area of sky in one day than Hubble in its first 25 years.