Friday, December 6 - Tonight there are craters galore to explore! Let's head to the Moon...
Just a short distance north of the southern cusp, look for a twin pair of craters on the terminator tonight. These are the craters Steinheil and Watt. The two are nearly identical in size, and overlap each other. Steinheil, named for mathematician, physicist, optician, and astronomer Karl August von Steinheil is just bit deeper and to the north. Watt, named for James Watt, Scottish engineer and first man to patent the use of a telescope for surveying, will show a wee bit more detail on its floor. For a telescopic challenge, remember the distance traveled south from Fabricus to this pair, and extend that distance even further south. Seen on the limb is crater Biela. If conditions are stable, you might pick up a tiny black point in Beila's west wall, Biela C.
Craters Steinheil and Watt - Credit: Damian Peach
For northern observers clamoring for brighter stellar action, look no further tonight than the incredible ""Double Cluster"" about four fingerwidths southeast of Delta Cassiopeiae (Right Ascension: 2:22.4 - Declination: +57:07). At a dark sky site, this incredible pair is easily located visually and stunning in any size binoculars and telescopes. As part of the constellation of Perseus, this double delight is around 7000 light-years away and less than 100 light-years separates the pair. While open clusters in this area are not really a rarity, what makes the ""Double Cluster"" so inviting is the large amount of bright stars within each of them. Well known since the very beginnings of astronomy, take the time to have a close look at both Chi (NGC 884) and H Persei (NGC869) very carefully. Note how many colorful stars you see, and the vast array of double, multiple and variable systems!
The Double Cluster - Credit: N.A.Sharp/NOAO/AURA/NSF
Saturday, December 7 - Today is the birthday of Gerard Kuiper. Born 1905, Kuiper was a Dutch-born American planetary scientist who discovered moons of both Uranus and Neptune. He was the first to know that Titan had an atmosphere, and he studied the origins of comets and the solar system.
Tonight let's return again to Cassiopeia and start at the central-most bright star, Gamma. Four degrees southeast is our marker for this starhop, Phi Cassiopeiae. By aiming binoculars or telescopes at this star, it is very easy to locate an interesting open cluster, NGC 457 (Right Ascension: 1:19.1 - Declination: +58:20), because they will be in the same field of view.
This bright and splendid galactic cluster has received a variety of names over the years because of its uncanny resemblance to a figure. Some call it an ""Angel,"" others see it as the ""Zuni Thunderbird;"" I've heard it called the ""Owl"" and the ""Dragonfly,"" but perhaps my favorite is the ""E.T. Cluster,"" As you view it, you can see why! Bright Phi and HD 7902 appear like ""eyes"" in the dark and the dozens of stars that make up the ""body"" appear like outstretched ""arm"" or ""wings."" (For E.T. fans? Check out the red ""heart"" in the center.)
NGC 457 - Credit: NOAO/AURA/NSF
All this is very fanciful, but what is NGC 457, really? Both Phi and HD 7902 may not be true members of the cluster. If 5th magnitude Phi were actually part of this grouping, it would have to have a distance of approximately 9300 light-years, making it the most luminous star in the sky, far outshining even Rigel! To get a rough idea of what that means, if we were to view our own Sun from this far away, it would be no more than magnitude 17.5. The fainter members of NGC 457 comprise a relatively young star cluster that spans about 30 light-years. Most of the stars are only about 10 million years old, yet there is an 8.6 magnitude red supergiant in the center. No matter what you call it, NGC 457 is an entertaining and bright cluster that you will find yourself returning to again and again. Enjoy!
Sunday, December 8 - Tonight let's take advantage of early dark and venture further into Cassiopeia. Returning to Gamma, we will move towards the southeast and identify Delta. Also known as Ruchbah, this long-term and very slight variable star is about 45 light-years away, but we are going to use it as our marker as we head just one degree northeast and discover Messier 103. As the last object in the original Messier catalog, M103 (NGC 581) was actually credited to Pierre Mechain in 1781. Easily spotted in binoculars and small scopes, this rich open cluster is around magnitude 7, making it a prime study object. At about 8000 light-years away and spanning approximately 15 light-years, M103 offers up superb views in a variety of magnitudes and colors, with a notable red in the south and a pleasing yellow and blue double to the northwest.
M103 - Credit: Hillary Mathis, N.A.Sharp/NOAO/AURA/NSF
Viewers with telescopes and larger binoculars are encouraged to move about a degree and half east of M103 to view a small and challenging chain of open clusters, NGCs 654 (Right Ascension: 1:44.1 - Declination: +61:53), 663 and 659! Surprisingly larger than M103, NGC 663 (Right Ascension: 1:46.0 - Declination: +61:15) is a lovely fan-shaped concentration of stars with about 15 or so members that resolve easily to smaller aperture. For the telescope, head north for NGC 654, (difficult, but not impossible to even a 114mm scope) which has a bright star on its southern border. South of NGC 663 is NGC 659 (Right Ascension: 1:44.2 - Declination: +60:42) which is definitely a challenge for small scopes, but its presence will be revealed just northeast of two conspicuous stars in the field of view.
Until next week? Ask for the Moon, but keep on reaching for the stars!
About Tammy Plotner - Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She's received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.