Euclid's visible and infrared instruments

ESA’s Euclid will examine visible and infrared light from distant galaxies using two scientific instruments on board. These instruments will measure the accurate position and shapes of galaxies in visible light, and their redshift (from which their distance can be derived) in the infrared light. With these data, scientists can construct a 3D map of the distributions of both the galaxies and the dark matter in the Universe. The map will show how large-scale structure evolved over time, tracing the role of dark energy.

The VISible instrument (VIS) takes very sharp images of galaxies over a much larger fraction of sky than would be possible from the ground. These observations will be used to measure the shapes of over a billion galaxies.

As the name suggests, VIS collects visible light. It is sensitive to wavelengths from green (550 nanometres) up to near infrared (900 nm). The instrument uses a mosaic of 36 CCDs (Charge Coupled Devices, a type of camera sensor), each of which contains more than 4000 pixels by 4000 pixels. This gives the detector a total of about 600 megapixels, equivalent to almost seventy 4K resolution screens.

Near-Infrared Spectrometer and Photometer (NISP) is dedicated to making spectroscopic measurements of galaxies, which involves determining how much light they emit per wavelength. This is useful for measuring the galaxies’ redshift, which cosmologists can use to estimate the distance to each galaxy. NISP has the largest field of view for an infrared instrument ever flown in space. The instrument measures near-infrared light (900–2000 nm) using a grid of 16 detectors, each containing more than 2000 by 2000 pixels.

Euclid is ESA’s space telescope designed to explore the dark Universe. The mission will create the largest, most accurate 3D map of the Universe ever produced across 10 billion years of cosmic time. Euclid will explore how the Universe has expanded and how large-scale structure is distributed across space and time, revealing more about the role of gravity and the nature of dark energy and dark matter.