Explanation: Stars can make waves in the Orion Nebula’s sea of gas and dust. This esthetic close-up of cosmic clouds and stellar winds features LL Orionis, interacting with the Orion Nebula flow. Adrift in Orion’s stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged Sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed. The small, arcing, graceful structure just above and left of center is LL Ori’s cosmic bow shock, measuring about half a light-year across. The slower gas is flowing away from the Orion Nebula‘s hot central star cluster, the Trapezium, located off the upper left corner of the picture. In three dimensions, LL Ori’s wrap-around shock front is shaped like a bowl that appears brightest when viewed along the “bottom” edge. This beautiful painting-like photograph is part of a large mosaic view of the complex stellar nursery in Orion, filled with a myriad of fluidshapes associated with star formation.
Explanation: City lights shine along the upper east side of Manahattan in this dramatic urban night skyscape from February 13. Composed from a series of digital exposures, the monochrome image is reminiscent of the time when sensitive black and white film was a popular choice for dimly lit night and astro-photography. Spanning 2 minutes and 40 seconds, the combined 22 frames look across the reservoir in New York City’s Central Park. Stars trail in the time-lapse view while drifting clouds make patterns in the sky. Traced from top to bottom, the dashed line in the surreal scene is the International Space Station still in sunlight and heading for the southeast horizon. The short time intervals between the exposures leave gaps in the space station’s bright trail.
Explanation: The comet PanSTARRS, also known as the blue comet (C/2016 R2), really is near the lower left edge of this stunning, wide field view recorded on January 13. Spanning nearly 20 degrees on the sky, the cosmic landscape is explored by well-exposed and processed frames from a sensitive digital camera. It consists of colorful clouds and dusty dark nebulae otherwise too faint for your eye to see, though. At top right, the California Nebula (aka NGC 1499) does have a familiar shape. Its coastline is over 60 light-years long and lies some 1,500 light-years away. The nebula’s pronounced reddish glow is from hydrogen atoms ionized by luminous blue star Xi Persei just below it. Near bottom center, the famous Pleiades star cluster is some 400 light-years distant and around 15 light-years across. Its spectacular blue color is due to the reflection of starlight by interstellar dust. In between are hot stars of the Perseus OB2 association and dusty, dark nebulae along the edge of the nearby, massive Taurus and Perseus molecular clouds. Emission from unusually abundant ionized carbon monoxide (CO+) molecules fluorescing in sunlight is largely responsible for the telltale blue tint of the remarkable comet’s tail. The comet was about 17 light minutes from Earth.
Explanation: One of our Solar System’s most tantalizing worlds, Enceladus is backlit by the Sun in this Cassini spacecraft image from November 1, 2009. The dramatic illumination reveals the plumes that continuously spew into space from the south pole of Saturn’s 500 kilometer diameter moon. Discovered by Cassini in 2005, the icy plumes are likely connected to an ocean beneath the ice shell of Enceladus. They supply material directly to Saturn’s outer, tenuous E ring and make the surface of Enceladus as reflective as snow. Across the scene, Saturn’s icy rings scatter sunlight toward Cassini’s cameras. Beyond the rings, the night side of 80 kilometer diameter moon Pandora is faintly lit by Saturnlight.
In the Heart of the Heart Nebula Credit & Copyright: AlanErickson
Explanation: What’s that inside the Heart Nebula? First, the large emission nebula dubbed IC 1805 looks, in whole, like a human heart. It’s shape perhaps fitting of the Valentine’s Day, this heart glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula’s center. In the heart of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their energetic light and winds. The open cluster of stars contains a few bright stars nearly 50 times the mass of our Sun, many dim stars only a fraction of the mass of our Sun, and an absent microquasar that was expelled millions of years ago. The Heart Nebula is located about 7,500 light years away toward the constellation of the mythological Queen of Aethiopia (Cassiopeia).