Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2007 June 26
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Wisps of the Iris Nebula
Credit & Copyright: Thomas V. Davis (

Explanation: Like delicate cosmic petals, these clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of flowers. Still, this beautiful digital image shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a massive, hot, young star in its formative years. Central filaments of cosmic dust glow with a reddish photoluminescence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Yet the dominant color of the central nebula is blue, characteristic of dust grains reflecting starlight. Dark, obscuring clouds of dust and cold molecular gas are present on the left of the image, and lead the eye to see other convoluted and fantastic shapes. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. As shown here, the bright blue portion of the Iris Nebula is about six light-years across.

Tomorrow's picture: neon saturn

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