What's Up this Week: November 27 – December 3, 2006
Written by Fraser Cain
Greetings, fellow SkyWatchers! Sister Selene is back en force, so why not take a few evenings to catch up on some lunar features? If you want to double your pleasure and double your fun – why not look at binary stars instead of just one! Time to dust off the telescope and head out into the night, because…
Here's what's up!
Monday, November 27 – On the lunar surface, the three rings of Theophilus, Cyrillus and Catharina will emerge, but tonight let's power up on Theophilus and see what we can find!
The area just northeast of Theophilus – where Mare Tranquillitatis and Mare Nectaris join – is called Sinus Asperitatis. Toward its center you will see the remains of a once grand nameless crater holding the younger, sharper Torricelli in its center. Dropping back to Theophilus, just outside of its east wall, you will also find a young crater – Madler. As you head east across the northern shore of Mare Nectaris, look carefully for two partial rings. The northernmost is so eroded that it never received a name, while a slight, faint horseshoe marks all that remains of Daguerre.
Now let's return to Delta Cephei and take a closer look. It is also a well-known double star that was measured by F .G. W. Struve in 1835. Its 6.3 magnitude companion has not shown change in position or separation angle in the 171 years since Struve looked at it. Chances are this means the two are probably not a physical pair, yet S.W. Burnham discovered a third, 13th magnitude companion in 1878. Enjoy the color contrast between its members.
Tuesday, November 28 – Tonight not only will the Moon and Uranus be close, but there will be an occultation. Please check IOTA for specifics in your area.
Are you ready for some more lunar work? Then let's start by identifying previous study Maurolycus.
Maurolycus is found about two Crisium lengths southwest of Theophilus and in tonight's light will appear especially fine. But look just north of Maurolycus to pick out the battered remains of Class III crater Gemma Frisius, an Astronomical League challenge. Spanning 56 miles and descending 17,100 feet below the lunar surface, you'll find its walls broken, yet enough of its northern boundary remains to clearly reveal the impact that created Goodacre. Look for the shadows which blend Goodacre and Gemma Frisius together.
Before we retire to the shadows tonight let's study small, open cluster NGC 225, located a finger-width northwest of Gamma Cassiopeiae. This 7th magnitude collection has been described by some as looking like a sailboat. A more fascinating description might be that of the "Metamorphosis Cluster"- since the southwest region of the cluster looks like a butterfly asterism and to the northeast is the caterpillar asterism. While just barely detectable as an unresolved patch through binoculars on a dark night, tonight's Moon means that magnification is needed just to make out its half dozen brighter 9th magnitude members. Modest scopes should reveal two dozen stars to magnitude 12.
Wednesday, November 29 – Tonight let's head back to the Moon's north towards the long scar of the Alpine Valley, also known as Valles Alpes. This easy to spot feature will help to find another challenge crater. Where the valley joins the lunar Alps, follow the range south into Mare Imbrium. Along the way you will see the protruding bright peaks of Mons Blanc, Promontorium DeVille, and at the very end, Promontorium Agassiz ending in the smooth sands. Southeast of Agassiz you will spot the Astronomical League challenge, Cassini. This shallow crater holds another challenge within – Cassini A. But look carefully, can you spot the B crater on Cassini's inner southwestern rim? Or the very small M crater just outside the northern edge?
Now let's return to Cassiopeia and explore its bright central star: 2.8 magnitude, 100 light-year distant Gamma is very unusual. Once thought to be a variable, it has been known to go through some very radical shifts in terms of temperature, spectrum, magnitude, color, and diameter. It is also a visual double star, but its close, disparate companion is not easy. At 11.0 magnitude, the companion is 3000 times fainter than the primary!
Four degrees southeast of Gamma is our marker for this starhop, Phi Cassiopeiae. By aiming binoculars or telescopes at this star, it is very easy to locate an interesting same-field open cluster – NGC 457. This bright and splendid galactic cluster has received a variety of names over the years due to its uncanny resemblance to various figures. Some call it an "Angel," others a "Zuni Thunderbird," It has been called the "Owl" and the "Dragonfly," and most recently the "E.T. Cluster." As you observe it through a telescope, it's easy to see why. Bright Phi and HD 7902 appear like eyes glowing in the dark and the dozens of stars that make up the body appear like outstretched arms or wings. (For E.T. fans? Check out the red "heart" star in the center.)
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 magnitude 5 Phi were part of the group, they would have to be at a distance of approximately 9300 light-years, making them the most intrinsically luminous stars in the sky – far outshining even Rigel and Deneb! To get a rough of idea of what this means, if we were to view our own Sun from that distance, it would be no more than magnitude 17.5. The fainter members of NGC 457 comprise a relatively "young" star cluster spanning some 30 light-years of space. Most members are about 10 million years old, yet there already is an 8.6 magnitude red supergiant in the center. No matter what you call it, NGC 457 is an entertaining and bright cluster you will find yourself returning to again and again. Share with your family and friends!
Thursday, November 30 – On this day in 1954, Elizabeth Hodges of Sylacauga, Alabama was struck by a 4 kilogram meteor after it crashed through the roof of her house and bounced off the radio. Duck!
There's no ducking lunar impacts, though…and tonight we'll have a look at the grandest impact of all, Class I crater Tycho.
Spanning 56 miles and descending 13,800 feet below lunar surface, Tycho's massive walls are 13 miles thick. As one of the youngest craters, Tycho might not look like much tonight, but it is surely one of the most impressive of all features when the Moon reaches Full. Look around Tycho for six small craters encircling it like an old analog telephone dial. To the southeast, another prominent feature calls attention to itself – Maginus. Power up and look closely at the more than 50 meteoritic impacts that have all but destroyed it. The very largest of the wall craters is on the southwest crest and is named Maginus C. On the outer north wall, look for less conspicuous Proctor. It, too, has been struck many times!
This evening Uranus is high in the south right after skydark. Although the planet was first cataloged as a 6th magnitude star (34 Tauri), it was the first outer planet discovered. At 5.8 magnitude, you'll find it slightly less than one degree south-southwest of 4th magnitude Lambda Aquarii. The nearest star that is similar in brightness is magnitude 6.1 variable FM Aquarii. Located a little more than three degrees south-southwest of Lambda, FM varies through pulsation (a Delta Scuti type) and ranges no more than 0.03 magnitudes every two hours.
Friday, December 1 – Born today in 1811 was Benjamin (Don Benito) Wilson, the namesake of Mt. Wilson, California.
The Moon is closest to Earth and tonight we'll start at the Carpathian Mountains directly north of mighty Copernicus' east wall. Some of these peaks reach as high as 6,600 feet and could have been formed from extruded lava. Can you trace them beyond the terminator? To the northeast, Eratosthenes shows very nicely. Continue about one Crisium length north of Copernicus for the sharp puncture of Class I Pytheas. Another half-Crisium length further north, discover a slightly larger, but less prominent, Class I crater – Lambert – residing on an unnamed ridge.
Tonight we know the name of our study, so set your sights on double star Alfirk (Beta Cephei). At magnitude 3.3, Alfirk is easily spotted as the northwesternmost star of the constellation Cepheus. Beta A is a hot, 3.5 magnitude, B-spectral type star accompanied west-southwest by a 13.6 arc second distant 7.8 magnitude blue companion. This one is comparable to Polaris in resolution, so take the opportunity to view both!
Saturday, December 2 – Today in 1934, the largest single mirror in telescope history took form as the blank for the 200-inch Mt Palomar Hale reflector was cast in Corning, NY.
Tonight peaceful Gassendi calls, but we'll visit the "Ocean of Storms" by taking a voyage across the southern Oceanus Procellarum.
Set sail from the port of Gassendi and head north to small crater Gassendi B. As you move across the grey sands, look for a serene wave following the southwestern shore. This is Dorsum Ewing and you'll see it trail south into the pockmark of Herigonius east of Gassendi B. East of Herigonius are two additional craters – the northernmost is Norman. Return again to Dorsum Ewing and follow it north where it leads to some low hills and the tiny crater Scheele and more prominent Wichmann even further north. If you look closely at Wichmann you will see it as a small impact on what appears to be the remains of a long-ago flooded, now terribly eroded crater. Ride the waves in the "Ocean of Storms" to see which port it takes you to!
Now we're off to Aquarius to resolve a stunning matched set of 4th magnitude stars separated by 2.1 arc seconds – Zeta Aquarii. To locate Zeta, start at Alpha and look due east about two finger-widths. Center on the pair and use as much power as sky conditions permit.
Sunday, December 3 – Today in 1971, Soviet Mars 3 became the first spacecraft to make a soft landing on the Red Planet. Two years later on this date Pioneer 10 was the first spacecraft to fly by Jupiter. One year later, Pioneer 11 did the same thing!
Tonight let us go from one extreme to another as we begin on the northernmost limb of the lunar surface. From the northernmost Sinus Roris, look for lens-shaped crater Markov. To Markov's northeast is a large, flat crater with very few distinguishing characteristics. Its name is Oenopides. If conditions are stable, look for a gray slash on the lunar limb further north of Oenopides known as Cleostratus. On the southern limb, look for familiar craters Wargentin, Nasmyth and Phocylides. Even farther south, note the long oval Pingre.
Be sure to look at the "field stars" around the Moon tonight, for the Pleiades are very, very close!
Now let's go to extremes on stars as we look for two doubles – one north and the other south. 4.0 magnitude Kappa Cephei is located a little more than a fist width southwest of Polaris. Center on Kappa at the lowest power and look for 8.0 magnitude Kappa B 7.4 arc seconds east-southeast. Now head for 4.5 magnitude 91 (Phi 1) Aquarii high in the south just after skydark. It's the westernmost member of a tangle of 4th and 5th magnitude stars – all called Phi! Look for its 8.5 magnitude companion leading it across the sky to the northwest. This 150 light-year distant pair has a blue dwarf for a secondary and an orange-yellow sub-giant primary.
May all your journeys be at light speed… ~Tammy Plotner with Jeff Barbour.
Filed under: What's Up
Comment policy: Be nice and brief. Don't advertise your stuff, or promote your personal theories. We'll delete any comments that break these policies. Click here for more details.