Artist’s impression of the Euclid Space Telescope
ESA
The European Space Agency (ESA) is gearing up for the launch of its newest space telescope, Euclid, which is scheduled to launch from Cape Canaveral, Florida, on July 1. Euclid is designed to solve his two greatest mysteries in the universe: dark energy and dark matter.
These two “dark” components make up more than 95 percent of the universe, but we can’t see them, hence the name, and we don’t know what they’re made of. Little do I know. Astronomers infer the existence of dark matter from the behavior of matter that we can see. Dark matter works as if there is a special gravitational force holding it all together. Dark energy has the opposite effect, causing an accelerating expansion of the universe as a whole.
Euclid has two scientific instruments: a visible-light camera that measures the shape of the galaxy, and a near-infrared detector that measures the brightness and distance of the galaxy. This isn’t the first space telescope to use either of these types of instruments, but it has cataloged over a billion galaxies spanning more than a third of the sky, observing vast swaths of the universe. It is unusual in that it is planned to
“The Hubble Space Telescope and the James Webb Space Telescope are great observatories for looking at very small areas with great sensitivity and amazing detail, but it’s a bit like looking at the Earth. Say ‘the sky through a little straw’ Mike Seifert Worked as a Euclid project scientist at NASA’s Jet Propulsion Laboratory in California. “At Euclid, we are more interested in measuring some properties of a very large number of galaxies, rather than properties of individual galaxies or objects.”
Researchers use these properties to construct two types of space maps. The first uses a phenomenon called gravitational lensing, in which relatively nearby matter is distorted, magnifying the light of objects behind it. By how this bends the apparent shape of distant objects, we can learn about the distribution of nearby matter acting as a lens.
Distortions are typically small, but the sheer amount of data Euclid is expected to collect during its six-year mission will allow researchers to use gravitational lensing to illuminate matter, including otherwise invisible dark matter. You should be able to map the distribution. How – in space. Knowing the distribution of dark matter more precisely could help us understand how it behaves and provide clues as to what it really is made of.
Another type of map uses ripples in the distribution of matter in the universe called baryon acoustic oscillations. These ripples first formed as sound waves shortly after the Big Bang, when the universe was a hot, swirling soup of particles and radiation. Eventually, that soup cooled and the waves froze in place, leaving a slightly denser region where more galaxies tend to form as the universe expands. Mapping the over-density of these relics could be a very effective way of examining how and why expansion is accelerating.
“Observing how the early cosmic wrinkles propagated forward and how dark energy affected them is critical to understanding the evolution of the universe, and how it actually works. It helps,” Seifert says. If all goes well, Euclid should soon start unraveling the mysteries of the universe.
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