What’s Up This Week – October 10 – October 16, 2005

Voyager photo of Neptune. Image credit: NASA/JPL. Click to enlarge.
Monday, October 10 – Today in 1846, William Lassell was busy at his scope as he made a new discovery – Neptune’s moon Triton! Although our everyday equipment can’t “see” Triton, we can still have a look at Neptune in central Capricornus. At near magnitude 8, Neptune will appear as no more than a near stellar-sized, slightly blue-tinged disc. You’ll find it just slightly less than a fingerwidth to the northeast of Theta Capricornii. While you might think finding Neptune is a bit disappointing visually, consider this… We’re able to see it 4.3 billion kilometers away! Not bad considering we’re on a planet that would fit inside its dark oval.

Tonight on the lunar surface, let’s return again to a favourite old feature. In the lunar north, you cannot help but see the long, deep scar of the Alpine Valley slashing its way across the lunar Alps. Power up and see if you can spot tiny crater Trouvelot on its eastern edge. Now let’s head north across Mare Frigoris for more! Perhaps you’ll spy Rimae Archytas near the terminator along the mare’s southern shore. As you head north across the smooth sands, look for the larger punctuations of Protogoras and Archytas on the northern shore. If you continue north, the ruined crater W. Bond will meet your eye, with its small eastern crater and crater Timaeus with its central peak caught on W. Bond’s southern wall.

Tuesday, October 11 – Tonight the lunar terminator will have moved to reveal another old familiar crater to the north – Plato. Let us use it as our guidepost and see what we can find!

To the casual eye, the interior of Plato would appear to be smooth, but if conditions are steady? Power up to the max. Inside you will find as many as five small craterlets. Along its outside western wall, look for a deep impact crater – A. Carefully note there is a long depression, perhaps caused by a glancing meteor strike, that angles off to the northwest from its northern wall crest that ends in a small crater! To the northeast, you might find a thin rimae, like a crack, that traces its way towards the beginning of the Montes Alpes. Head north again across Mare Frigoris and you will see the remains of crater Birmingham and Epigenes between it and last night’s W. Bond. Look further north for the shallow Goldschmidt with the younger Anaxagoras intruding upon its west wall. And, of all the craters to the very north? What better name to give one than Byrd – for the American polar explorer!

Wednesday, October 12 – Today in 1892, astronomy great E. E. Barnard was hard at work. Using photography, he became the first to discover a comet -1892 V – in this way.

With lunacy, our best shot is a morning comet that you’d almost need a camera for – C/2003 K4 LINEAR scooting across Eridanus. While this is not an easy comet – large telescopes only – at roughly magnitude 12.5, we’d like to thank SkyHound for this excellent chart. Good luck!

Tonight on the Moon, let’s take an in-depth look at one of the most impressive of the southern lunar features – Clavius.

Although you cannot help but be drawn visually to this crater, let’s start at the southern limb near the terminator and work our way up. Your first sighting will be the large and shallow dual rings of Castatus with its central crater and Klaproth adjoning it. Further north is Blancanus with its series of very small interior craters, but wait until you see Clavius. Caught on the southeast wall is Rutherford with its central peak and crater Porter on the northeast wall. Look between them for the deep depression labeled D. West of D you will also see three outstanding impacts C, N and J, while CB resides between D and Porter. The southern and southwest wall are also home to many impacts and look carefully at the floor for many, many more! It has been often known as a test of a telescope’s resolving power to see just how many more craters you can find inside tremendous old Clavius. Power up and enjoy!

Thursday, October 13 – Today marks the founding of the British Interplanetary Society in 1933. “From imagination to reality”, the BIS is the world’s longest established organization devoted solely to supporting and promoting the exploration of space and astronautics.

Tonight we’ll do them proud as we have a look at newly revealed crater, Longomontanus.

Northwest of last night’s study – Clavius – Longmontanus is also a crater with many wonderful details. As you power up to observe, note that it has obliterated a much older crater whose remains can be seen just outside its east wall. Inside Longomontanus, you’ll see a very small collection of central peaks and a terrific series of smaller impacts on its northwest wall. Now let’s concentrate outside Longomontanus’ north wall as we identify the remains of Montanari with an impact on the ruins of its west wall. Due east is the double strike of crater Brown. As we continue north, we see crater Wilhelm with its multiple strikes between its south wall and Montanari’s north. Look for a series of four small impacts which separate it and Heinsus to the north.

Friday, October 14 – Tonight the Moon’s peaceful crater Gassendi will call, but we’re about to set sail on the “Ocean of Storms” as we visit the southern section of Oceanus Procellarum.

Let’s leave from the port of Gassendi and head north to small crater Gassendi B. As you move out onto the grey sands, look for a serene wave which follows the southwestern shoreline. Its name is Dorsa Ewing and you will see it trail south into the pockmark of Herigonius almost due east of Gassendi B. To its east you will see two additional craters, and the northernmost is Norman. Return again to Dorsa Ewing and trace it north where it leads into some low hills and the tiny crater Scheele and far more prominent Wichmann further north. If you look closely a Wichmann you will see it is a small impact on what looks to be the remains of a long flooded, and terribly eroded crater. Ride the waves in the “Ocean of Storms” and see to what ports it takes you!

Saturday, October 15 – Today in 1963 marks the first detection of an interstellar molecule. This discovery was made by a group headed by Sander Weinreb using the MIT Millstone Hill 84-foot dish. Using new correllation receiver technology, hydroxyl molecules were found as absorption bands using the supernova remnant Cas A as a background continuum source. By the dawn of the new millenia, nearly 200 different interstellar molecules had been identified and many of these are considered organic in nature.

Tonight let’s see what might be up there in the region of Cas A using visible light shall we? The nearest bright star to Cas A is magnitude 2.4 Caph (Beta Cas) – the brightest and most westward of the stars making up the Cassiopeia “W”. To locate the region of Cas A, sweep about 6 degrees due west of Caph and follow the subtle curve of three 5th magnitude stars. Cas A lies less than one degree south-southwest of the second star in the sequence of three. That star is a complex 4.9 magnitude multiple star system associated with variable star AR Cas.

Through binoculars two stars of this system are easily resolved – the 4.9 magnitude primary led across the sky by a 7.1 magnitude secondary. The 76 arc second distant secondary (component C) is actually a very tight double itself having a 1.4 arc second separated 8.9 magnitude partner which should be resolvable in fine 4 inch instruments. The very finest, large-apertured amateur scopes may also be able to distinguish a 9.3 magnitude 0.9 second B-component from the 4.9 magnitude primary. Smaller scopes are back in the running again when attempting three 11th magnitude stars – none of which are closer than 42 arc seconds to the primary. Intermediate apertured scopes can also hope to pick out a 12.9 magnitude H component 27 arc seconds northwest of the 7.1 magnitude C component. 8.9 magnitude F also has a 9.1 magnitude near twin 11 arc seconds east-northeast. If you can see them all you should probably wrap an observatory building around your telescope – if one isn’t there already!

If you like to follow brightness changes in variables – AR Cas is not a good choice. This eclipsing type variable only fluctuates by a tenth of a magnitude over a period 6 earth days!

When we are finished, let us go from one extreme to another as we begin on the northernmost limb of the lunar surface. From the northernmost portion of Sinus Roris, look for the lens-shaped crater Markov. To the northeast you will spy a large, flat looking crater with very little distinguishing characteristics whose name is Oenpides. If conditions are very stable, you might stand a chance at a grey slash on the very lunar edge further north known as Cleostratus. On the southern end we see familiar craters Wargentin, Nasmyth and Phoclides, but go to the very southern limb – the long oval is named Pingre.

Sunday, October 16 – Tonight after the Sun sets, let’s take a look at where Venus is now! Using binoculars, you’re in for a real treat as you will notice that Antares is also in the same field of view. Now look again unaided. This bright pair are only separated by about 1.5 degrees. Watch again tomorrow night as they move further apart.

Tonight the great Grimaldi will capture the eye, but head southeast for another featureless dark grey oval, Crueger. The next crater south is hard to see, because it really doesn’t appear like a crater. Its name is Darwin, and it is “evolved” to the point where it is best caught by focusing on its rimae which includes its east wall. Look for a Y formation pointing towards Crueger.

Before you think I’m finished with you, I’m going to ask western American observers to get up early. Why? Because there will be a partial lunar eclipse tomorrow morning! The Earth’s shadow will just nick the edge of the Moon and only around 7% will go dark. While this is just a minor event, I’d get up early to watch and perhaps you will, too! You’ll find much more information on this event here on NASA’s pages. Wishing you clear skies!

Until next week? Ask for the Moon, but keep reaching for the stars! May all your journeys be at light speed…. ~Tammy Plotner