Around the Moon in 28 Days: Lunar Observing for Beginners

Course Notes

Section 27 - Lunar Day 22

Section 28 - Lunar Day 23

Section 29 - Lunar Day 24

Section 30 - Lunar Day 25

Section 31 - Lunar Day 26

Section 32 - Lunar Day 27

Section 33 - Lunar Day 28 (The End)

Copyright © 2010 Mintaka Publishing Inc. 2

Section 27 - Lunar Day 22

Tonight's late rising Moon might seem impossible to study when you have a daytime work schedule, but why not consider going to bed early and spending the early morning hours contemplating some lunar history and the peace and quiet before the day begins? Let's journey off to the lonely Riphaeus Mountains just southwest of crater Copernicus. Northeast of the range is another smooth floored area on the border of Oceanus Procellarum. It is here that Surveyor 3 landed on April 19, 1967.

Figure 27-1: The major features of the Moon on Day 22

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Figure 27-2: Surveyor 3 and Apollo 12 and 14 landing sites (courtesy of NASA)

After bouncing three times, the probe came to rest on a smooth slope in a sub-telescopic crater. As its on-board television monitors watched, Surveyor 3 extended its mechanical arm with a "first of its kind" miniature shovel and dug to a depth of 18 inches. The view of sub-soil material and its clean-cut lines allowed scientists to conclude that the loose lunar soil could compact. Watching Surveyor 3 pound its shovel against the surface, the resulting tiny "dents" answered the crucial question. The surface of a mare would support the landing of a spacecraft and exploration by astronauts!

Now return to Copernicus, and this time head north for distinguished little Class I Pytheas. Like a bright, small ring standing alone in the southern half of dark Mare Imbrium, this high contrast feature will catch the eye. Just a bit more to the north is motley Lambert. Although it is marginally larger, notice how much darker it appears. Lambert stands on a great lunar ridge winding its way up from grand Eratosthenes 420 kilometers southeast, and the ridge continues on for another 240 kilometers. As you observe, you may notice the ridge is just slightly lighter than the background. While Lambert isn't as splashy as its neighbor to the east – Timocharis - you might catch the sunlight reflecting off the hollowed-out remains of its central peak. This

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may be a collapsed area of a "rebound dome” - a formation created when the crater formed during a particularly nasty impact. Can you see the bright point of crater Euler to the west? Euler is roughly the same size as Lambert and Pytheas - but has a noticeably higher central peak. If the timing is right, you may be able to see the peak of Mons Vinogradov peeking above the terminator to the west.

Figure 27-3: Surveyor 3 self-portrait deploying shovel (courtesy of NASA)

Figure 27-4: Crater Pytheas (courtesy of Damian Peach)

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Section 28 - Lunar Day 23

The slender, silent Moon is once again lit with Earthshine. As we stand here in the moments before dawn, we behold the "New Moon In the Old Moon's Arms". We've almost come full circle, haven't we? There's still more to learn...

Figure 28-1: The major features of the Moon on Day 23

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Before daylight comes, we journey to the lunar surface in search of crater Focault. To find it, head north to the silent C-shape of Sinus Iridum and locate the punctuation of crater Bianchini in the center of the ring of Juras Mountains. Just northeast, and near the shore of south- eastern Mare Frigoris, look for a bright little circle – crater Foucault. Physicist Jean Foucault played an instrumental role in the creation of today's parabolic mirrors. His "Foucault knife edge test" made it possible for opticians to test mirror curves for optical excellence during the final phases of shaping before metallization. Thanks to Foucault's insight, we can turn our telescopes on difficult objects such as double stars... or tiny craters!

Figure 28-2: Craters around Sinus Iridum

To the west of Sinus Iridum, you'll see another prominent crater in the highlands - Mairan. This 39-kilometer-diameter impact crater has a very dark floor which helps it stand out against the lighter background. Shadows pick up the steep walls. Power up in a telescope and take a look at its slopes where you'll discover many little craterlets dotting the terraces and steps. At

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first glance in binoculars, or a low power, its wide floor might seem rather plain, but if you magnify you'll find it also has a mountain peak, craterlets and hills! Further south is the very narrow sinuous rille known as the Rimae Mairan which extends for about 61 miles and helps form the shoreline of Sinus Roris.

Figure 28-3: Crater Mairan (courtesy of Damian Peach)

If you follow through to the south, you will encounter Mons Gruithuisen Delta, Mons Gruithuisen Gamma and crater Gruithuisen - a wonderful series of volcanoes and their namesake. Mons Gruithuisen Gamma is often called the "Topsy Turvy Bathtub". While you might not find these features particularly impressive, consider that we're looking at something only 20 kilometers wide and only 900 meters high! Can you resolve the small craterlet at the peak? Just look at all the incredible things you have learned in less than a lunar month!

Figure 28-4: - Mons Gruithuisen region (courtesy of Damian Peach)

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Section 29 - Lunar Day 24

This morning we'll work in the south and start by identifying the long narrow ellipse of crater Schiller. Further south along the terminator, look for a line of four prominent craters. Their interiors may be black, but the southeast walls will be brilliantly illuminated. The most striking of this quartet is Zucchius which, depending on libration, may be very shadowed. To its east is Bettinus, and at power you will see central peaks in both craters.

Figure 29-1: The major features of the Moon on Day 24

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Further southeast is Kirchner, and to its east is the very old Wilson. Just north of Bettinus and - at an angle to Zucchius - you will see a strange, walled, V-shaped area curving back to Schiller. This odd area is one of the Moon's older surface features. An eon or two ago, this was part of a much larger structure which can be traced here and there amidst later forming craters. Since all that is now left is some hills and ridges, no one is certain if the area formed geologically or was caused by an impact.

Figure 29-2: The region around Crater Schiller (courtesy of Peter Lloyd)

Now let's head a bit north...

In 2006, SMART 1 went into the history books as it impacted the lunar surface in Lacus Excellentiae. Launched on September 27, 2003 by ESA, it entered lunar orbit over a year later on November 13, 2004. After operating 5000 hours through 483 starts and stops, the xenon- ion engines ran out of fuel in September 2005, but not before the mission successfully completed its mapping studies. Although the craft caused a brief flash on the surface as it ended its life, it left an indelible mark on history - one almost as important as that left in 1959

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by the first craft to impact the Moon, Luna 2. You'll find Lacus Excellentiae and the SMART 1 site just south of Mare Humorum and just north of Schiller. It smashed into the western shore very near a large peak!

Figure 29-3: SMART One Impact Flash courtesy of NASA

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Section 30 - Lunar Day 25

Even though the atmosphere and growing daylight will greatly trouble any observations this morning, there is no harm in at least looking for the challenging punctuations of Cardanus and Krafft – an area also visible on Lunar Day Thirteen (as illustrated here).

Figure 30-1: The major features of the Moon on Day 25

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Southern Cardanus' circular formation is typical of the Upper Imbrian period and is in excess of 3 billion years old. Spanning about 51 kilometers in diameter, its high terraced walls reach up about 2300 meters. Look for shadow play to the south which will reveal how the lunar surface slopes upward, almost drift-like. If skies are steady, power up and try to resolve the challenging little bright point of Cardanus M along the interior wall. To Cardanus' north is Cantena Krafft, a 61 kilometer long crater chain whose geological timeline origins are unknown. If you follow the series of small impacts on their trajectory northwards, you'll Moon walk right into the southern wall of 53 kilometer wide crater Krafft. Stand on its rimae and look down at the floor 1250 meters below. Krafft was formed at the same time as its southern neighbor, but it's taken a much more recent and violent impact on its eastern wall in the form of Krafft C.

Figure 30-2: Cardanus and Krafft Region (courtesy of Peter Lloyd)

Both Cardanus and Krafft are youngsters compared to the more northern walled plain of Struve. Named for the great Russian astronomer, Friedrich Georg Wilhelm von Struve, this ancient formation is probably in excess of 4 billion years old. Easily spotted in binoculars, the 175 kilometer wide area has a height that's impossible to calculate because of its angle. If skies are steady, power up in a telescope and look at how the old lava flows have connected it

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to crater Russell to the north. Like Struve, western Eddington was also formed in the pre- Nectarian geological period and is equally old. What separates this 138 kilometer wide lava plain from its western counterpart? Just a wall... one that we can see, but can't get an accurate shadow measurement on. We know it's high enough to have kept the two from blending together like the shadowy remains of the craters which border to their south. If libration is favorable, look for challenging 71 kilometer wide Balboa along the limb or 98 kilometer wide Vasco de Gama. Both are "on the edge" features!

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Section 31 - Lunar Day 26

This morning we'll first visit the northern cusp to take a last look at crater Anaximander just north of J. Herschel. Depending on exactly how many hours old the terminator is at your time of viewing, you may be able to catch of glimpse of its 2800 meter high walls and the tremendous impact which collapsed them when crater Carpenter slammed into life shortly after it was born around 4 billion years ago. If shadow play is right, you may see Anaximander A, which is bordered by two mountains. Look for long shadows along the southwest wall - there is a good reason for them - they rise over 2900 meters above the lunar surface. That's as tall as Mount Francais - the highest peak on the Antarctic Peninsula!

Figure 31-1: The major features of the Moon on Day 26

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As you slide south along the limb edge, you'll encounter the long, dark well of Pythagoras. This very young crater occurred after its southeast neighbor, Babbage, slamming into the lunar surface and creating a hole 130 kilometers wide and 4800 meters deep. To give you an idea of just how impressive that is, it's even deeper than undersea Oahu Honolulu Volcanic Series - part the volcanic chain which formed the Hawaiian Islands known. Depending on the sunlight angle, you may see that Pythagoras has a lava flooded floor, which only gives rise to a double central peak and a few low hills and depressions. Even as impressive as Pythagoras is, it did very little but blemish 148 kilometer wide Babbage. This walled plain was standing some 2 million years before and still remains. But, Babbage isn't without its battle wounds, either... Look for the awesome impact of C which left a gaping hole in its western interior! Whatever impact originally caused Babbage happened after Oneopides, because if you look carefully, you'll see Babbage's walls supersede its structure.

Figure 31-2: Pythagoras Region (courtesy of Peter Lloyd)

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Section 32 - Lunar Day 27

If we were only to view the Moon in respect to the stars - the sidereal period - it would take 27 days 7 hours 43.2 minutes for our tour to complete an orbit and our time would be drawing to within hours of a close. However, our Earth-Moon system is also orbiting the Sun and this means it takes just a little while longer to return to the exact same phase from which we started. For all intents and purposes of this course, we've marked our lunar days by the time it takes the Moon to make one complete orbit around the Earth and come back to the same place. As we've learned though, a lot depends on the time zone in which you live and exactly the point in time marked on our reference charts as to when the Moon officially begins its age. So let’s say our time hasn't ended yet!

Figure 32-1: Earthrise over the Moon as seen from Apollo 8 (courtesy of NASA).

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In space exploration, a lunar day is the period of time it takes for the Moon to complete one full rotation on its axis with respect to the Sun - essentially the same as our lunar day here on Earth. When humans first began exploring the Moon up close, we saw our own world with new eyes when Bill Anders aimed the 270mm lens on a Hasselblad camera towards our "pale blue dot" and captured one of the most profound images of all time - Earth seen from another world. It was made into a postage stamp and hailed as the "Greatest Photo of the 20th Century". But, just as our Moon has not stopped its inexorable path back towards the Sun- neither did lunar exploration.

Figure 32-2: Earthset as seen from the Kayuga lunar probe (courtesy of JAXA).

On October 18, 2007 the Japan Aerospace Exploration Agency (JAXA) and NHK (Japan Broadcasting Corporation) went into space history as the lunar explorer "Kaguya" successfully transmitted the world's first high-definition image of "Earth Set" from lunar orbit. Cruising above the Moon at an altitude of 100 km, Kaguya (Japanese for "SELENE" - SELenological and ENgineering Explorer) has so far been the largest lunar mission since the Apollo program. The craft studied the Moon’s elemental and mineralogical composition, its geography, its surface and sub-surface structure, the remnant of its magnetic field, and its gravitational field. Scientists also gained a better understanding of the plasma, the electromagnetic field and high-energy particles near the Moon- paving the way for possible future human exploration and utilization.

Kayuga’s mission concluded when the craft impacted the Moon on command from Earth on June 10, 2009.

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Section 33 - Lunar Day 28

With only hours - or perhaps minutes - to go before the Moon returns to "New", one of the most supreme challenges you will ever face as a lunar observer will be spotting the ultra-thin crescent on this final day of the lunar cycle. It will require an absolutely open horizon and very clear skies. Like the Day One challenge, the Moon is so near to the Sun that your window of opportunity may be only minutes, or you may not have one at all depending on the your timing and location. Scanning the horizon with binoculars can help, but be very careful not to slip across the disc of the rising Sun as you scan!

Regardless of whether or not you see this morning's Moon, take a good look at all you have learned in the last lunar month. Remember- these challenges were meant to delight and intrigue you – whether you are a beginner or seasoned sky watcher. You may have enjoyed some perfect evenings when many of the lunar features described here in this book will come very easy to you, while other evenings may have proved more difficult. Before you become discouraged, remember there is no "time limit" to the Moon! It will wait for you, and return again each month as it has for billions of years.

When skies aren't clear, or if you simply have a little spare time- try to improve your Moon- watching skills by making simple sketches or finalizing your notes and observing lists. And use your down time to study up! The Internet offers a huge library of lunar data and images that were simply unavailable to the lunar observer many years ago. You'll find a great list of recommended links in the index section which make for perfect reading, along with downloads that will help to aid you in identification, timing, and even predictions of your own.

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As you prepare yourself to return again to the beginning of the lunar cycle, don't forget to gently share your "lunacy" with others. Not all family members, friends or acquaintances will feel the same about your hobby, but what a wonderful thing if they do! Many times children and teenagers will discuss their problems and life concerns far more readily when they are comfortable "in the dark" gazing up at the sky with a loved one. Sometimes simply sharing the peace and pleasure of observing the Moon and stars can form lasting bonds.

And now we have reached the end... Only to return to the beginning!

Around the Moon in 28 Days: Lunar Observing for Beginners