2024-10-16 13:49:00
Giga has long been the new mega in many areas of consumer electronics. However, 208 gigapixels is still an impressive image size. This is the completeness of the recording that ESA Director General Josef Aschbacher and Carole Mundell, scientific director of the European Space Agency, presented on 15 October at the International Astronautical Congress in Milan.
This is a mosaic of 260 individual observations that the special European space telescope Euclid made over a section of the southern starry sky between March 25 and April 8 this year. The image appears, so to speak, as the first volume of a huge celestial atlas, which the instrument was launched to create on July 1, 2023, to its observation post in a solar orbit at 1.5 million kilometers from Earth.
At 132 square degrees, the image covers about 500 times what the disk of the full moon observed from Earth covers. About one hundred million astronomical light sources can be seen here. Mostly these are stars from the Strait of Mich, that is, from our galaxy, but, like zoom Video shows in an exemplary way the alien galaxies, whose shape, distance and speed Euclid can measure with respect to our position in space. In fact, the mosaic image now published contains around 14 million such galaxies. The sky map that Euclid is supposed to create is a three-dimensional atlas of galaxies as they actually exist in space – and is in fact the largest that has been tackled to date.
In addition to the point sources of the stars and the disks of the galaxies, a veil can be seen, which in this illustration stands out in blue against the black of the intergalactic cosmos. This is gas and dust in our Milky Way that reflects collective starlight. Due to its appearance it is also called “galactic cirrus”.
The image now released covers just 1% of what Euclid is expected to capture over the course of its six-year mission. The finished atlas will then measure around two billion galaxies, up to the distances from which light has traveled to us for ten billion years. One of the main goals of this project is to accurately map the distribution of dark matter in the universe on a large scale. This matter – if it is such – has so far been perceived only through its gravitational fields; its physical nature is unknown;
It is also hoped that the Euclid Atlas will provide new data on the even more mysterious so-called dark energy. This is the reason for the accelerating expansion of the universe, discovered only almost 25 years ago. So far it appears that this is an immutable phenomenon over cosmic time periods – in other words, a cosmological constant. Recently, however, there have been the first, still vague, signs of a slowdown.
Last but not least, the question of the cosmological constant and the inconsistencies between the different methods for determining the current expansion rate of the cosmos mean that astrophysicists await with growing interest the first publication of the cosmological results of Euclid’s data. It is scheduled for 2026.
Before that, the next volume of the Altas is scheduled to be published in March 2025, covering another 53 square degrees. Since the telescope began scientific operation in February 2024, 12% of the entire target area has been observed. Due to various visibility limitations caused by the belt of the Milky Way and its galactic cirrus clouds as well as the accumulation of dust in the orbit of the planets of our solar system, this corresponds to only 36% of the entire firmament. Even the most complete galactic atlas ever created will therefore have recorded and measured only a small fraction of the observable universe. This contains at least one hundred billion galaxies.
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