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.
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. Explanation:Does the blue nebula look like the head of a witch? The nebula isknown popularlyas the Witch Head Nebula because, it is said, the nebula's shape resembles aHalloween-style caricatureof a witch's head. Exactly how, though, can be a topic ofimaginative speculation. What is clear is thatIC 2118is about 50light-yearsacross and made of gas and dust that points to -- because it has been partly eroded by -- the nearby starRigel. One of the brighter stars in the constellation Orion,Rigellies just below the center of thefeatured image. The blue color of the Witch Head Nebula and is caused not only byRigel's intense blue starlightbut also because thedust grainsscatter blue light more efficiently than red. The samephysical processcauses Earth's daytimesky to appear blue, although the scatterers in planetEarth's atmosphereare molecules ofnitrogenandoxygen.Tomorrow's picture:suddenly Saturn