The dark Horsehead Nebula and the glowing Orion Nebula are contrasting cosmic vistas. Adrift 1,500 light-years away in one of the night sky's most recognizable constellations, they appear in opposite corners of the above stunning mosaic. The familiar Horsehead nebula appears as a dark cloud, a small silhouette notched against the long red glow at the lower left. Alnitak is the easternmost star in Orion's belt and is seen as the brightest star to the left of the Horsehead. Below Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. The magnificent emission region, the Orion Nebula (aka M42), lies at the upper right. Immediately to its left is a prominent reflection nebula sometimes called the Running Man. Pervasive tendrils of glowing hydrogen gas are easily traced throughout the region.

Was there ever another comet like ISON? Although no two comets are exactly alike, one that appears to have had notable similarities was Comet Kirch, the Great Comet of 1680. Like approaching Comet ISON, Comet Kirch was a bright sungrazer, making a very close approach to the surface of the Sun. Neither comet, coincidently, is a member of the most common group of sungrazers -- the Kreutz group -- populated by remnants of a comet that disintegrated near the Sun hundreds of years ago. The long tail of Comet Kirch is depicted in the above painting by Lieve Versheier. As pictured, some members of the foreground crowd of Rotterdam in the Netherlands are holding cross-staffs, an angle measuring device that predated the sextant. No one knows how Comet ISON will develop, but like Comet Kirch, it is expected to be brightest when very near the Sun, in ISON's case during last few days of November. Gallery: Bright Comets of 2013

Arcing toward a fiery fate, this Sungrazer comet was recorded by the SOHO spacecraft's Large Angle Spectrometric COronagraph(LASCO) on December 23, 1996. LASCO uses an occulting disk, partially visible at the lower right, to block out the otherwise overwhelming solar disk allowing it to image the inner 8 million kilometers of the relatively faint corona. The comet is seen as its coma enters the bright equatorial solar wind region (oriented vertically). Positioned in space to continuously observe the Sun, SOHO has now been used to discover over 1,500 comets, including numerous sungrazers. Based on their orbits, the vast majority of sungrazers are believed to belong to the Kreutz family of sungrazing comets created by successive break ups from a single large parent comet that passed very near the Sun in the twelfth century. The Great Comet of 1965, Ikeya-Seki, was also a member of the Kreutz family, coming within about 650,000 kilometers of the Sun's surface. Passing so close to the Sun, Sungrazers are subjected to destructive tidal forces along with intense solar heat. This small comet, known as the Christmas Comet SOHO 6, did not survive. Later this year, Comet ISON, potentially the brightest sungrazer in recorded history but not a Kreutz sungrazer, is expected to survive.

Found among the rich starfields of the Milky Way toward the constellation Cassiopeia, star cluster NGC 7789 lies about 8,000 light-years away. A late 18th century deep sky discovery of astronomer Caroline Lucretia Herschel, the cluster is also known as Caroline's Rose. Its suggestive appearance is created by the cluster's nestled complex of stars and voids. Now estimated to be 1.6 billion years young, the galactic or open cluster of stars also shows its age. All the stars in the cluster were likely born at the same time, but the brighter and more massive ones have more rapidly exhausted the hydrogen fuel in their cores. These have evolved from main sequence stars like the Sun into the many red giant stars shown with a yellowish cast in this lovely color composite. Using measured color and brightness, astronomers can model the mass and hence the age of the cluster stars just starting to "turn off" the main sequence and become red giants. Over 50 light-years across, Caroline's Rose spans about half a degree (the angular size of the moon) near the center of the wide-field telescopic image.

Point your telescope toward the high flying constellation Pegasus and you can find this expanse of Milky Way stars and distant galaxies. Centered on NGC 7814, the pretty field of view would almost be covered by a full moon. NGC 7814 is sometimes called the Little Sombrero for its resemblance to the brighter more famous M104, the Sombrero Galaxy. Both Sombrero and Little Sombrero are spiral galaxies seen edge-on, and both have extensive central bulges cut by a thinner disk with dust lanes in silhouette. In fact, NGC 7814 is some 40 million light-years away and an estimated 60,000 light-years across. That actually makes the Little Sombrero about the same physical size as its better known namesake, appearing to be smaller and fainter only because it is farther away. A very faint dwarf galaxy, potentially a satellite of NGC 7814, is revealed in the deep exposure just below the Little Sombrero.

Warm shades and subtle colors come to the sky in the fading sunlight after shadowrise on this little planet. Of course the little planet is planet Earth, and this nadir-to-zenith, around-the-horizon mosaic maps the view from a small airfield near the town of Intendente Alvear, La Pampa province, Argentina. Just above the western horizon (top) the sky shines with the warm colors of sunset. The slate blue shadow of Earth itself extending through the atmosphere can be seen rising as it hugs the eastern horizon (bottom). Wrapped closely above the narrow projection of Earth's shadow is the gentle glow of reddened, backscattered sunlight called the antitwilight arch or the Belt of Venus.

If you climbed this magnificent tree, it looks like you could reach out and touch the North Celestial Pole at the center of all the star trail arcs. The well-composed image was recorded over a period of nearly 2 hours as a series of 30 second long, consecutive exposures on the night of October 5. The exposures were made with a digital camera fixed to a tripod near Almaden de la Plata, province of Seville, in southern Spain, planet Earth. Of course, the graceful star trails reflect the Earth's daily rotation around its axis. By extension, the axis of rotation leads to the center of the concentric arcs in the night sky. Convenient for northern hemisphere night sky photographers and celestial navigators alike, the bright star Polaris is very close to the North Celestial Pole and so makes the short bright trail in the central gap between the leafy branches.

For reasons unknown, NGC 6357 is forming some of the most massive stars ever discovered. One such massive star, near the center of NGC 6357, is framed above carving out its own interstellar castle with its energetic light from surrounding gas and dust. In the greater nebula, the intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. The overall glow of the nebula results from the emission of light from ionized hydrogen gas. Near the more obvious Cat's Paw nebula, NGC 6357 houses the open star cluster Pismis 24, home to many of these tremendously bright and blue stars. The central part of NGC 6357 shown spans about 10 light years and lies about 8,000 light years away toward the constellation of the Scorpion.

This image of Saturn could not have been taken from Earth. No Earth based picture could possibly view the night side of Saturn and the corresponding shadow cast across Saturn's rings. Since Earth is much closer to the Sun than Saturn, only the day side of the ringed planet is visible from the Earth. In fact, this image mosaic was taken earlier this month by the robotic Cassini spacecraft now orbiting Saturn. The beautiful rings of Saturn are seen in full expanse, while cloud details are visible including the polar hexagon surrounding the north pole, and an extended light-colored storm system.

This colorful skyscape features the dusty, reddish glow of Sharpless catalog emission region Sh2-155, the Cave Nebula. About 2,400 light-years away, the scene lies along the plane of our Milky Way Galaxy toward the royal northern constellation of Cepheus. Astronomical explorations of the region reveal that it has formed at the boundary of the massive Cepheus B molecular cloud and the hot, young, blue stars of the Cepheus OB 3 association. The bright rim of ionized hydrogen gas is energized by the radiation from the hot stars, dominated by the bright blue O-type star above picture center. Radiation driven ionization fronts are likely triggering collapsing cores and new star formation within. Appropriately sized for a stellar nursery, the cosmic cave is over 10 light-years across.

The bulging center of our Milky Way Galaxy rests on a pillar of light in this luminous skyscape. Recorded on September 22nd in dark South African skies, rivers of dust seem to flow downward from the galactic center towards Antares, yellowish alpha star of the constellation Scorpius, near the top of the scene. The brightest celestial beacon present is not a star at all though, but planet Venus, still dominant in the western sky after sunset. Of course, the pillar of light stretching upward from the horizon is Zodiacal light. Sunlight scattered by dust along the plane of the ecliptic creates the zodiacal glow, prominent in the evening after twilight during the southern hemisphere spring.

In order top to bottom this celestial snapshot features Comet ISON, planet Mars, and Regulus, alpha star of the constellation Leo, in the same frame. The scene spans about 2 degrees near the eastern horizon in early morning skies of October 15. Closest of the three, the much heralded Comet ISON (C/2012 S1) is by far the faintest at 14 light-minutes (1.7 AU) away. Mars is only slightly farther from our fair planet. About 16.5 light minutes (2 AU) away its normal ruddy color is washed out in the exposure. Regulus outshines both comet and planet from a distance of 75 light-years. Just above Regulus, the very faint smudge of light is actually the Leo I dwarf galaxy, 800,000 light-years away and almost lost in the glare of the bluish hued bright star. Comet ISON is expected to grow brighter, though. How bright is still not clear, but not as bright as a Full Moon in night skies. Estimated to be 1 to 4 kilometers in diameter, ISON's nucleus might substantially survive its very close encounter with the Sun on November 28. If so, the comet will climb back above the eastern horizon in planet Earth's northern hemisphere before dawn in early December.