Space weather
Euclid is a space mission, for a very good reason: on the surface of Earth, “ground-based” telescopes are subject to sunlight during the day, varying temperatures, to clouds, humidity, wind, and sometimes even rain. They are subject to a constantly varying atmosphere – the consequences of ‘weather’. Euclid’s core science, cosmology, however, requires a telescope with very stable properties – not possible in ground-based weather – so Euclid had to go to space. In contrast, is the Sun-Earth-Lagrange-Point-2, where Euclid is now stationed, the most perfectly stable place? Well, not completely. We’ll tell you why.
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