Euclid telescope: Scientist reports on his quest to understand the nature of dark matter and dark energy
On July 1, 2023, Euclid, a unique European space telescope was launched from Cape Canaveral. The launch was undoubtedly the highlight of my career as an astronomer, but witnessing the result of years of work being put on ...
Euclid is the next big step forward in our quest to try to understand the universe. Over the past century we have made tremendous progress. We have learned that the fusion of hydrogen into helium powers stars like our sun, while most of the atoms in our bodies were forged in the cores of stars that have since exploded. We discovered that the galaxy is one of many galaxies that trace enormous foam-like structures that permeate the cosmos. We now know that the universe started about 13.6 billion years ago with a "Big Bang" and has been expanding ever since.
Probing the universe's black box
These are major achievements, but as we learned more, it also became clear that there is much that we do not understand. For instance, most of the mass is believed to be "dark matter," a new form of matter that is not explained by the otherwise highly successful standard model of particle physics. The gravitational pull of all this matter should slow down the expansion of the universe, but about 25 years ago we found that it is actually speeding up. This requires an even more mysterious component. To reflect our ignorance—to date, no good physical explanation exists—we refer to it as "dark energy." Combined, dark matter and dark energy make up 95% of the universe, but we do not understand their nature.
Figure 1. Euclid image of the Perseus cluster of galaxies. The large, yellow galaxies are part of this massive clump of matter, but we can discern another 50,000 distant galaxies. Credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, Fourni par l'auteur
Figure 2: This picture shows Euclid’s field-of-view against the size of the full moon. A single exposure is about 100x that of the Hubble Space Telescope, while its sharpness is almost the same. Credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, Fourni par l'auteur
Figure 3: Euclid image of IC 342, a spiral galaxy near the plane of the Milky Way. Euclid’s sensitive observations at near-infrared wavelengths, reveals many details in this galaxy. Credit: ESA, Fourni par l'auteur