The Pleiades in Red and Blue

Explanation: If you have looked at the sky and seen a group of stars about the size of the full Moon, that's the Pleiades (M45) . Perhaps the most famous star cluster in the sky, its brightest stars can be seen even from the light-polluted cities . But your unaided eye can also see its nebulosity -- the gas and dust surrounding it -- under dark skies . However, telescopes can catch even more. The bright blue stars of the Pleiades, also known as the Seven Sisters , light up their surrounding dust, causing it to appear a diffuse blue that can only be seen under long exposures. But that's not all. The cosmic dust appears to stretch upward like ethereal arms . And the entire structure is surrounded by a reddish glow from the most abundant element in the universe: hydrogen. The featured image is composed of nearly 25 hours of exposure and was captured last year from Starfront Observatory , in Texas , USA

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