

This image of the Horsehead Nebula in Orion was selected Astronomy Picture of the Day for Nov. 26, 2008.One of the most identifiable nebulae in the sky, the Horsehead Nebula is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on a photographic plate in the late 1800s. The red glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. A blue reflection nebula dubbed NGC 2023 surrounds the bright star at the lower left. The darkness of the horsehead is caused mostly by thick dust, although the lower part of the horsehead's neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming. Light takes about 1500 years to reach us from the Horsehead Nebula. (Adam Block, Mount Lemmon SkyCenter, University of Arizona)

This image of two galaxies catalogued as Arp 273 was selected Astronomy Picture of the Day for Nov. 18, 2008. The two prominent stars in the foreground of this colorful skyscape are well within our own Milky Way Galaxy. Their spiky appearance is due to diffraction in the astronomer's telescope. But the two eye-catching galaxies in view lie far beyond the Milky Way, at a distance of about 200 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters. From our perspective, the bright cores of the galaxies are separated by about 80,000 light-years. Cataloged as Arp 273 (also as UGC 1810), the galaxies do look peculiar, but interacting galaxies are now understood to be common in the universe. (Adam Block, Mount Lemmon SkyCenter, University of Arizona)

Artist's concept of the Mount Lemmon SkyCenter. (Illustration: Mount Lemmon SkyCenter, University of Arizona)
What better way to start off the new year than getting your first view of Mercury through the eyepiece of the University of Arizona Mount Lemmon SkyCenter's 24-inch telescope on the 9,157-foot summit of the Santa Catalina Mountains north of Tucson?
Especially when the General Assembly of the United Nations has declared 2009 as the International Year of Astronomy to celebrate the 400th anniversary of the first scientific use of a telescope by Galileo Galilei. IYA 2009, as it's called, has also been endorsed by UNESCO, the International Astronomical Union, and the U.S. Congress. The National Science Foundation, NASA and private donations support the U.S. part of the worldwide celebration.
UA's Mount Lemmon SkyCenter will host many special programs and events throughout the 2008 year-end holiday season and on into IYA 2009, including many that will be uniquely special to Mount Lemmon. The SkyCenter offers a professional-quality telescope that guests will use to view Mercury, help NASA target a shot at the moon, and find their place in the universe.
SkyNights guests can participate as part of a small observing group or reserve the telescope all night and be treated as a visiting astronomer. Reservations can be made by telephone, 520-626-8122, or by e-mail, skycenter@as.arizona.edu. Gift certificates are available for all SkyNight programs and workshops, also by phone and email.
Special SkyNights in early 2009 include:
More information about special "SkyNights" planned for early 2009 can be found on the Web at http://skycenter.as.arizona.edu.
The evening SkyNights program costs $48. To register and for more information, call Block or Cathi Duncan at Steward Observatory, 520-626-8122.
Valerie Grindle
520-626-6488
Adam Block
520-626-8122