Sent into space to pursue the dark and mysterious structures of the universe, Euclid's mission is both difficult and important. It is estimated that 95% of the universe consists of dark matter and energy. Researchers have a hard time finding evidence for these dark structures because their presence causes minute and subtle changes in the appearance and motion of objects we can observe. For this reason, the information that can be obtained from the data regarding the celestial bodies that Euclid would observe in the depths of the universe is quite valuable and important.
The Euclid space mission was organized and prepared by the European Space Agency (ESA). 15 countries and 2,000 scientists contributed to the preparation of this space telescope, its cameras and other equipment. Euclid is a space observatory that includes a 1.2 m diameter telescope and two scientific instruments that will record in the visible and infrared regions of the electromagnetic spectrum. This observatory, which has both imaging and spectral capabilities, is planned to continue its observations for at least six years at the Sun-Earth Lagrange-2 point, 1.5 million km away, in the neighborhood of the Gaia and James Webb satellite telescopes. Euclid will be able to take images at least four times sharper than those taken by advanced telescopes on Earth.
The first images show that the Euclid Space Telescope (EUT) and its cameras are performing extremely well, and that astronomers can use it to study the distribution of matter in the universe and its changes on the largest scales. Sharp images covering a large area of sky (larger than the area covered by the full moon) have the potential to reveal traces of darkness and hidden things. Euclid will provide us with information about the physics of stars and galaxies, as well as dark matter and energy research. Routine scientific observations of Euclid will begin in early 2024, following final fine-tuning.
Over the next six years, the EUT will make observations to reveal the shapes, distances and motions of billions of galaxies out to about 10 billion light-years away, in order to reveal dark influences or traces in the observed universe, thus generating data to create the largest three-dimensional cosmic map ever made. As the mission continues, Euclid's data will be released once a year and made available to scientists. What is special about the EUT is its ability to photograph a very wide area in a single image very sharply, in the visible and infrared energy regions. The first images from Euclid clearly demonstrate these important features.
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The Dark Side of the Universe:
Dark matter holds galaxies together, causing them to spin faster than expected based on the amount of visible matter they contain. Additionally, scientists find the existence of this unknown or unobservable matter among the galaxies possible because the bending of light from the galaxies behind it (gravitational lensing) can be detected through observations. Dark matter, also called missing mass, interacts only with light and normal matter through gravity. Euclid will make observations to understand how dark matter is distributed. It will measure how the structure of matter in the universe is changing and the effects of gravitational lensing.
Astronomical measurements in the 1990s showed that the rate of expansion of the universe was increasing. This was not an expected situation because it was impossible to explain it with the physical knowledge of that time. The universe has been expanding continuously since the Big Bang, but it was assumed that this rate of expansion would slow down over time due to the gravitational pull of all matter in the universe. Based on the name dark matter, the source of this acceleration in expansion was called "dark energy".
According to current research results obtained using data from ESA's Planck mission, dark energy contributes 9668 percent to the matter-energy budget of the universe. Dark energy is added to theoretical models as a "cosmological constant" to explain the current expansion rate of the universe. However, dark energy may not be constant and may change over time. Perhaps dark energy is a new fundamental force that unifies the four forces we currently know of: electromagnetic, weak and strong interactions, and gravity. Today, understanding the nature of dark energy remains one of the most difficult research topics in cosmology and physics. Euclid will map more than a third of the sky using the distribution of galaxies over the past 10 billion years of cosmological history. Looking back in time could provide important clues to understanding how dark energy is accelerating the expansion of the universe. Euclid, which is expected to measure the acceleration of the universe much more precisely, may show whether the dark energy used as the cosmological constant is constant or not. In addition, the theory of general relativity will be tested for the first time on such a large scale and over such a long time period, thanks to Euclid's observations.
Euclid will allow cosmologists to investigate these two competing dark mysteries: dark matter and energy.