Gravitational lensing, a remarkable phenomenon where dark matter warps space and reveals its hidden mass through its interaction with light, is about to be extensively explored by the European Space Agency’s (ESA) latest venture—the Euclid mission. Launched in 2023, Euclid aims to map out gravitational lensing events across the cosmos, with expectations to identify more than 170,000 strong gravitational lenses.

What is Gravitational Lensing?

But what exactly is gravitational lensing? Originally predicted by Einstein’s theory of general relativity, this phenomenon occurs when massive objects—like galaxies or even clusters of galaxies—bend the fabric of space-time, resulting in an intriguing magnification of light from more distant celestial bodies. This optical effect can produce fascinating visual phenomena, including luminous arcs, multiple images, and stunning Einstein rings, where distant objects appear encircled by bright light.

Insights into Cosmic Structure

By observing these gravitational lensing events, scientists can gain profound insights into the cosmic structure—investigating the distribution of both dark matter, which makes up about 27% of the universe, and dark energy, responsible for the mysterious accelerated expansion of space that comprises another 68%. The clear understanding of these components is essential for unlocking the mysteries of how galaxies form and evolve over time.

Euclid Wide Survey (EWS)