May 15 at 9:00 p.m., looking South
Night Sky May 2005
Last month, we learned about the dragon lurking in the northern sky. This month, we will explore the sea monster that resides in the southern sky. Hydra is the largest of the eighty-eight modern constellations in the sky. Covering 1,303 square degrees of the sky, the stars stretch along the southern horizon from Libra in the south-southeast to Cancer in the west-southwest. Despite its size, there is only one bright star, Alphard, at a magnitude of 1.98. An interesting star, R Hydrae, is a variable star with a period of 387 days. It ranges in magnitude between 3.5, easily visible to the naked eye, to 10.9, when a telescope is required to see it.
There are several multiple stars that should be visible using binoculars. Beta Hydrae is a binary consisting of a 4.8 and a 5.6 magnitude star (larger magnitude numbers indicate dimmer stars). Epsilon Hydrae is a collection of four stars ranging in brightness from 3.8 to 12.7 magnitudes. N Hydrae is a star pair just a bit brighter than magnitude 6.
For those who wish to break out the telescope, NGC5694 is an open star cluster just above the last tail star of Hydrae. It is believed that NGC5694 has plunged through the Milky Way's disk and may now be escaping into intergalactic space. A long tail stretching a thousand light-years from the “head” is believed to be the result of the dive through our galaxy. Also look for the Pinwheel Galaxy, M83, to the west of NGC 5694. This magnificent object has well-defined spiral arms and displays a very dynamic appearance, appealing with the red and blue knots tracing the arms. The red knots are apparently diffuse gaseous nebulae in which star formation is just taking place, and which are excited to shine by its very hot young stars. The blue regions represent young stellar populations that have formed within the last few million years or so. Between the pronounced spiral arms are regions with fewer stars. Dark dust lanes follow the spiral structure throughout the disk, and may be traced well into the central region to the nucleus, which is composed of an older yellowish stellar population that dominates the whole central region.
Today, Hydra guards Crater, the cup of water, from Corvus, the Crow, denying him a drink for all eternity.
Remember Sedna? It's that icy object uncovered last year in the outer reaches of the Solar System. Orbiting far beyond Pluto, there is considerable discussion about its place in the solar system: is it, or is it not, a planet? When it was first discovered, astronomers noticed it rotated once every twenty days. The only explanation of this slow rotation was a moon, but a moon never showed up in any of their observations. Scott Gaudi, a researcher with the Harvard Smithsonian Centre for Astrophysics, has been carefully watching the rotation of Sedna. He thinks it is only rotating once every ten hours or so. So, what about its moon? It never existed. Easy come, easy go.
With Jupiter just past opposition, it is time to get out your binoculars. Four of Jupiter's moons, Io, Europa, Ganymede, and Callisto, are easily visible with a good set of binoculars. Over the course of several hours, you can watch Io and Europa move. Over the course of several days, the outer moons also flop from one side of Jupiter to the other. Using a small telescope, you may be able to watch as the shadow created by a moon passing in front of the planet moves across the face of Jupiter.
For instance, Europa will transit (move across the front of) Jupiter on May 2, beginning at 7:30 p.m. MDT and finish at 10:15 p.m. Io follows a few hours later. Its transit begins at 12:20 a.m. and ends at 2:30 a.m. This dance continues nightly, so keep watching.
The effort to protect our dark skies in Sandoval County is moving. Many have requested a postcard to send to the county commission, but we need more. Check outside the Merc near the Signpost rack for cards, or ask inside Video and More in the Homesteads Shopping Center. The Bernalillo Barber Shop, across from the courthouse, also has cards. If you have not sent in a card, please get one and mail it. E-mail firstname.lastname@example.org.
I will keep the automatic reply updated with locations.
The Albuquerque Astronomical Society and the Sandia Ranger District will cohost an evening of free public stargazing in the Manzanos on Saturday, April 30, at Oak Flat Picnic Area. This will be the first event of the season for the popular Saturday-evening stargazing series. Other 2005 stargazing dates are May 14, June 11, July 30, August 27, and September 10.
The dark skies of the East Mountains and the large telescopes of TAAS astronomers together provide great views of planets, as well as more elusive deep-sky objects such as galaxies, nebulae, and star clusters.
Observing begins at sunset, weather permitting, and is suitable for all ages. Picnic facilities are available for those who would like to come early, and adjacent parking is available. Alcoholic beverages and pets are not allowed in the telescope viewing area.
To get there, take NM Highway 337 nine miles south of Tijeras, and follow the signs to Oak Flat and Juniper Loop. For more information and a map, visit www.taas.org or call 254-TAAS.