Samedi 20 décembre sera une date symbolique importante pour l’aérospatiale. Pour la première fois en effet, une femme se déplaçant en fauteuil roulant va

Une équipe de recherche internationale, comprenant des chercheurs CNRS de l'Observatoire de Paris - PSL, annonce la découverte d'une nouvelle exoplanète en orbite autour d'un système d'étoiles…

This astrophotography image features NGC 1499, widely known as the California Nebula, a large emission nebula located in the constellation Perseus. The nebula lies approximately 1,000 to 1,500 light-years from Earth and is one of the most impressive wide-field deep-sky objects in the northern night sky. NGC 1499 earned its nickname due to its elongated shape, which closely resembles the outline of the U.S. state of California when captured in long-exposure images. With an apparent size of nearly 2.5 degrees, the nebula spans about five times the diameter of the full Moon, corresponding to a physical length of roughly 100 light-years. The California Nebula is classified as a H-II region, consisting mainly of ionized hydrogen gas. It emits light predominantly in the H-alpha wavelength (656 nm), making it an ideal target for narrowband astrophotography. The nebula’s glow is powered by intense ultraviolet radiation from the nearby hot O-type star Xi Persei (ξ Persei, Menkib), which excites the surrounding hydrogen gas and causes it to shine. This image highlights the nebula’s delicate filamentary structures, faint outer regions, and complex dust lanes embedded within the glowing hydrogen clouds. These features reveal dynamic interactions between stellar radiation, interstellar gas, and dust - key processes linked to star formation within our galaxy. Discovered in 1885 by astronomer Edward Emerson Barnard, NGC 1499 is now considered a classic target in astrophotography. Due to its large size and low surface brightness, it is difficult to observe visually but reveals remarkable detail in long-exposure, H-alpha, and deep-sky imaging. The California Nebula is best photographed from the Northern Hemisphere during autumn and winter under dark skies.