Lab 4: The Moon / Lab Supplement

Sections

  1. Student Preparation which includes Quiz Preparation.
  2. Special Instructions For Instructors See also Diane Smith's Instructor Notes.
  3. Startup Presentation
  4. Short Definitions
  5. Post Mortem

  1. Student Preparation

    2.  Required Lab Preparation:

    1. Required Reading: Lab 4, Appendix D, Appendix G. It is hard to understand equipment without first seeing and playing with it, but insofar as possible you should be ready to use the telescopes.
    2. Read the Startup Presentation.
    3. Read IAL 3: The Moon: Orbit, Phases, Eclipses, and More section 4 only on the lunar phases and IAL 12: The Moon and Mercury sections 1--8 only.
    4. Read the Post Mortem. Better before than after actually.
    5. Read Short Definitions.
    6. Read a sufficient amount of the articles linked to the following terms etc. so that you can define and/or understand the terms etc. at the level of our class: CCD image, crater central peak, exposure time, impact crater, lunar craters (see Wikipedia: List of craters on the Moon), lunar geology, lunar highlands, lunar mountain range (see Wikipedia: List of lunar mountain ranges), lunar phases, mare (see Wikipedia: List of maria on the Moon), Moon (near side of the Moon, far side of the Moon), multi-ring crater, naked eye astronomy, rayed craters, rille (AKA rima) (see Wikipedia: List of lunar rilles), selenographic coordinates, selenography, sinuous rille, star diagonal, terraced crater, walled plain.

    Supplementary Lab Preparation: The items are often alternatives to the required preparation.

    1. Bennett (2008 edition): p. 42--45 on lunar phases, p. 271--274 on lunar geology or the corresponding pages in similar books.
    2. Wikipedia: Lunar phase
    3. Wikipedia: Lunar geology

    Quiz Preparation:

    The quiz might be omitted if it's not feasible or convenient. The students may or may not be informed ahead of time of quiz omission depending on the circumstances.

    The quizzes in total are 40 % of the course grade. However, only the top five quiz marks are counted.

    In preparing for a quiz, go over the Required Lab Preparation.

    The Supplementary Lab Preparation (see above) could help, but is only suggested if you feel you need more than the required Required Lab Preparation.

    There is no end to the studying you can do, but it is only a short quiz.

    One to two hours prep should suffice.

    There will be 10 or so questions and the time will be 10 or so minutes.

    The questions will range from quite easy to challenging.

    There may or may not be a prep quiz to test yourself with ahead of the lab period.

    The solutions might be posted at Moon: Quiz Solutions. after the quiz is given. Whether they are or not depends on the circumstances of each individual semester.

  2. Special Instructions For Instructors

    1. Check as needed:
      1. Usual Startup
      2. Usual Shutdown

    2. As usual for inside-outside labs, check the weather online at NWS 7-day forecast, Las Vegas, NV in advance and by personal visual inspection at/during the lab period.

      In case the weather is not good for observing, you need to have an alternate indoor lab ready.

      Usually the alternative should come from the current semester Lab Schedule. If that is NOT possible, yours truly suggests Lab 16: Hubble's law since that is pretty short and easy and takes little prep.

      On the other hand, you could do all the inside part on the bad night and do the rest next week if the Moon is still in a good position.

      Someone will make an executive decision.

    3. Since this is a Moon observation lab, you should also check what the current phase is.

      1. You could check the preceding days by eye.
      2. But usually you'll want a sky map. The Moon has to be above the horizon to see it.

        The sky map below has to be updated for the observation night.

      3. USNO: What the Moon looks like now
      4. USNO: Lunar Phase Calculator: You have to type in the time data yourself which is a nuisance.
      5. stardate.org lunar phase calender of the month: This is convenient image showing the lunar phases for the whole month.
      6. USNO: Fraction of the Moon Illuminated: Another calculator, but only midnight (beginning of date) and noon are available. But one can interpolate intermediate values.

    4. You will need to set up the C8 telescopes on the roof before the lab period and review their usage well in advance if needed.

      The C8's can be sky aligned for this lab, so that the Moon stays fixed in the field of view while the students sketch it.

      But on the other hand, the Moon is easy to find and the students can keep it in view by continually adjusting their scopes.

      So sky alignment is optional for The Moon lab.

      See Telescope Operation for procedures and tips.

      Since the Moon is likely to be near full moon (since that is when it is best to do the The Moon lab), one should put the Moon filters to save the eyes from glare.

        The Moon filters are in the box labeled Moon filters.

        They screw on and off the bottom of the 40-mm eyepieces.

        Don't screw them on too tight.

        If you have to shoot through clouds, you should leave the Moon filters off. The clouds will probably provide more than enough filtering.

      Diane Smith's Instructor Notes suggest taking off the star diagonals.

      But I suggest leaving them on. The orientation is easy to get: Tycho is at the mid-south, Kepler is at the mid-east (on the sky).

      Direct naked-eye observations of the Moon while sketching should give the students the right orientation anyway.

      It is possible to cover all parts of the lab in one week, but be sure to decide among the instructors how to proceed in order to avoid chaos on the roof.

      As many C8's as needed should be set up and the instructors should decide ahead of time how to share them.

    5. If you let students use smaller focal length eyepieces than the standard 40 mm one, make sure at the end of the night that the non-standard ones are collected and back in their boxes and the 40 mm eyepieces are back on the C8's.

    6. The lab formally requires setting up a CCD camera and demonstrating its use.

      When the class is present take a Moon image showing the class the steps. Then put the image on the dome computer, transfer it somehow to the computer in the telescope control room (Bigelow Physics Building (BPB) 230), and then transfer the image to the lab computers for the students to process as part of the lab.

      See CCD Camera Instructions.

      But you only need to set up the CCD camera and take an new image if you really, really want to.

      It's a lot of extra bother for the instructors for what it is worth to the students.

      You can just provide the students with an old image to process such as moon_2013_02_21_waxing_gibbous.FIT or moon_2013_02_26_full.FIT.

      Actually, students can often take Moon images with their cell phones. That's a lot more fun for them. We can't process the images, but often they look great anyway.

    7. In the lab room, you will need to set on each table a Moon globe and a large Moon map.

      Post the largest poster Moon map on the bulletin board.

    8. Startup Presentation:

      Go over some of the following items: lunar phases, tidal locking, (AKA synchronous rotation), lunar geology, and lunar features.

      Use images to illustrate the items.

  3. Startup Presentation

    1. Hand back old reports and quizzes.

    2. Start 7:30 pm sharp.

    3. Give tonight's agenda: quiz, post mortem on the last lab, Startup Presentation, lab. In my view, the Startup Presentation should only be about 10 minutes---the lab is an active learning environment.

    4. Then give the quiz. It will be 10 minutes or so. Late arrivals have to write the quiz at the tables in the hall.

    5. Give the post mortem of the last lab. Be brief.

    6. Then tell them to form new groups, report to a computer, launch Firefox, click down the chain Jeffery astlab on bookmarks, Lab Schedule, tonight's lab, and srcoll down past the foxes.

    7. Objectives:

      In this lab, we go from "low tech", the naked-eye sketch, to "high tech", the CCD image---which we usually don't take ourselves.

      The observing part of the lab is intended to proceed this way:

      1. Naked-eye sketches: Everyone does their own. Don't give up until you have marked on as much as you can. It takes a bit of staring to see everything that you can.

      2. Every group does a telescopic sketch. Mark on a lot of features: maria. lunar craters, rayed craters, central-peak craters, lunar mountain ranges, walled plains, rilles.

        Walled plains and especially rilles might challenging to identify.

        You should take turns sketching. One person will see what another will not.

        Prominent features or especially obvious isolated features in the maria are good things to sketch since they are easiest to find later in the lab on the Moon map.

      3. A CCD image will be taken on the lab night or has been taken in the past.

        For the new image case, every group will get a copy of the CCD image.

        For the past case use moon_2013_02_21_waxing_gibbous.FIT or moon_2013_02_26_full.FIT.

        Use the one whose phase is closest to the phase of the lab night.

        Download the image from here or find it in the Lab 4 folder or someplace else on the computers. To fill in the image data, use today's date and the approximate time of your observations, and leave the other data items blank.

        Process and analyze the new or old image just as directed in the lab manual.

      4. You all should see where the Moon is in the sky right now---see the figure below.

      5. What is the lunar phase right now---see the figure below:

    8. The Big Picture:

      Now let's get the big picture from the Moon map of near side of the Moon shown below.

    9. Formation of the Moon:

      In the giant impact hypothesis, the Moon formed about 4.5 Gyr ago from debris ejected from the Earth by the giant impactor.

      This was very early on in solar system evolution since the Solar System formed about 4.6 Gyr ago. (Wikipedia: Formation and evolution of the Solar System: Timeline of Solar System evolution).

      The giant impact hypothesis is a pretty robust theory, but there are still doubts about aspects of it.

    10. Cratering After Formation:

      After formation of the Solar System, there was a heavy bombardment that carried on from maybe carried on until maybe about 3.8 Gyr ago. There may have been an especially active late heavy bombardment (4.1--3.8 Gyr).

      There was no sharp ending to the heavy bombardment. The cratering continues to the present present at a probably continually declining rate.

      In the heavy bombardment, planetesimals, asteroids, and meteoroids rained down on the Solar System astro-bodies including themselves.

      The result was heavily cratered surfaces.

      The rocky astro-bodies with long-term internal-heat driven geology largely erased the early impact craters and later ones too.

      Internal-heat driven geology is increases with mass.

      The large bodies Earth and Venus have relatively few impact craters and none from heavy bombardment,

      From Mars down in mass, the rocky astro-bodies are heavily cratered.

      The general rule, the smaller the astro-body, the more cratered until one gets so small that there is probably a saturation.

      The Moon is heavily cratered in the lunar highlands mostly from the heavy bombardment.

      The lunar highlands are the original lunar surface.

    11. The Maria:

      The maria were formed when giant impactor smashed the lunar surface and created giant basins that were then flooded by lava from the deep interior.

        The singular is mare, pronounced "mar-ray". The plural is maria which is often used instead of mare as if it were a singular form.

      Calling them maria (Latin for seas), the early telescopic were sort of right---not seas of water, but seas of frozen lava.

      The maria formed after the heavy bombardment, and thus are far less cratered than the lunar highlands.

      The maria are also far darker than the lunar highlands.

      This makes them distinctive and easy to identify.

      The maria and the most prominent lunar craters on the near side of the Moon are displayed in the figure below.

      The maria make up only about 16 % of the lunar surface, but they are mostly on the near side of the Moon and mostly not right on limb (the visible edge), where their projected area would be small. (see Wikipedia: Lunar mare).

      Thus, the maria seem much more extensive than they are, in fact.

      The far side of the Moon (which we never see from Earth) is rather uninteresing to look at because it lacks large maria. See the image below.

    12. Rayed Craters:

      When impactors hit, they can throw hot giant plumes of material that fall back to form ray features radiating from impact craters.

      Such impact craters are rayed craters.

      In some cases, the rays can extend far around most of the impacted astro-body.

      The rays are obliterated eventually by subsequent geological activity.

      On the Moon, this subsequent geological activity is further impacts by impactors large and small.

      Thus only the relatively young lunar craters show conspicuous rays.

      Crater Tycho is the most obvious rayed crater on the Moon.

      Even small telescope observation reveals Tycho and its rays.

      Without its rays and its relatively young bright appearance, Tycho would not be nearly as obvious as it is. It's not the largest crater in its immediate neighborhood.

      Tycho is obvious in the labeled Moon map above.

      It is also obvious in the false-color image below.

    13. Central-Peak Craters and Terraced Craters:

      Now let's look at Crater Copernicus.

    14. Walled Plains:

      A walled plain is a large lunar crater whose interior has been flooded by lava.

      Typically walled plain diameters are between 60 and 300 km.

      The lava plain is usually pretty smooth except for smaller lunar craters from impactors after the formation of the lava plain.

      There is no crater central peak or only one sticking through the lava plain???. The original central peak, if any, has been buried or partially buried??? by the lava.

      Walled plains are NOT a distinct species since there is a continuum from smaller lunar craters of similar structure to lunar maria which actually large versions of walled plains---the the Oceanus Procellarum may be an excepiont---it may have been formed by a rifting process at least in part (see Gibney, E. 2014, Nature, Oct01, Moon's largest plain is not an impact crater).

      Lunar maria, however, do not usually have a single unbroken crater rim as walled plains usually do.

      Online definitions walled plain are rather deficient. The best seems to be Peter Grego, 2004, Moon Observer's Guide, p. 17. See also Inconstant Moon: Walled Plains & Ring Mountains.

      Crater Archimedes is a good example of a walled plain. See the image below.

    15. Multi-Ring Craters:

      Multi-ring craters have multi rings.

      The rings may have been shock waves expanding from the impact site that simply froze in place.

      Multi-ring craters seem to be a rare but they are also spectacular since they are large.

      The only two yours truly has ever heard of are Orientale Basin on the Moon and the Caloris Basin on Mercury.

      The Orientale Basin is shown in the figure below.

    16. Rilles:

      Let's now look at a rille (AKA a rima).

      In large surface images they often look like wormy lines.

      Up close they can look like smoothed ditches as the figure below shows.

      The origin of rilles is still a bit debated and since there are different kinds, there may be different origins.

      However, they are long depressions that are some kind of lava flow channels.

      Some of the rilles may be collapsed lava tubes---underground lava flow channels.

      We have lava tubes on Earth. The nearest one is probably the Lava River Cave Flagstaff, Arizona---which the locals just call the lava tubes.

      On the Moon, there are known lunar lava tubes.

    17. Lunar Mountains and Lunar Mountain Ranges:

      What are lunar mountains?

      Well the few kinds I know are:

      1. Crater Rim Mountains:

        The smooth crater rims of lunar craters can be considered mountains in a sense.

        But many of the things we would obviously call lunar mountains and lunar mountain ranges are the fragments of the crater rims.

        Cratering by further impactors on top of the crater rims is the major cause of the fragmentation.

        The most prominent mountain ranges are the fragmented rims of the mare impact basins that later flooded with lava to become the maria.

        Montes Recti shown in the figure below may have been part of a very large crater rim.

      2. Crater Central Peaks:

        Crater central peaks are an isolated kind of lunar mountain. They are formed by the rebound of the lunar surface to the impact of the impactor. Central peaks are approximately in the centers of the impact craters and are usually heavily eroded by space weathering and diurnal temperature cycling.

      3. Lunar Domes:

        There are also lunar domes which are a kind of shield volcano. They are probably not a very common feature since they are seldom mentioned.

        The figure below shows lunar domes, but not very clearly.

      4. Lunar Lobate Scarps:

        The lunar lobate scarps: relatively small ridges extending only a few miles with heights up to 100 m.

        Stretching a point, one might call them lunar mountains. But probably most people would NOT call them lunar mountains---and so we won't either, except when we do.

        The lunar lobate scarps seem to have formed within the last few hundred million years.

        As the lunar interior cools and contracts a little??? over geologic time, the Moon, and consequently the rigid lunar surface cracks and buckles to form the lunar lobate scarps.

        Mercury has similar, but much larger, Mercurian lobate scarps.

      There are probably other kinds of lunar mountains too---but that's enough for here.

      There don't seem to be any fold mountains that are common on our fair planet Earth. Fold mountains are a result of plate tectonics which the Moon does not have and probably never had---at least not in any obvious way.

    18. Lunar Phases:

      You've all seen the lunar phases---don't deny it.

      The animation below will remind you.

      Now simple lunar phase questions often seem very difficult to people.

      But once you get the hang of them, they are easy.

      They are sort of analogous to a problem in algebra with one equation and THREE VARIABLES.

      You can solve for any ONE variable if you know the other TWO.

      The three "variables" are:

      1. Lunar phase or phase of the Moon.

      2. Location of Moon in the sky: eastern horizon, eastern sky, near the meridian western sky, western horizon, and somewhere below the horizon.

        Remember the Moon is always near the ecliptic: i.e., in a day it will be carried around with the celestial sphere on almost the same arc on the sky as the Sun.

      3. Time of solar day: e.g., sunrise, noon, sunset, and midnight. (Time is also the same as location on the Earth in these problems.) People often find this the hardest one to solve for if it is unknown.

      ONE DIAGRAM---which you can reproduce for yourself whenever you need it---allows you to answer all such phase questions.

      See the figure below.

      For some fun with lunar phases, you should play with the applet below which dynamically illustrates the lunar phases.

    19. Tidal Locking (AKA Synchronous Rotation):

      Tidal locking takes a lot of explaining.

      So I suggest you read IAL 3: he Moon: Orbit, Phases, Eclipses, and More: Lunar Rotation and Tidal Locking

      The animation below gives some insight into tidal locking.

    20. We won't take new CCD camera images.

      We will just process old images:

      1. moon_2013_02_21_waxing_gibbous.FIT For waxing gibbous moon nights.
      2. moon_2013_02_26_full.FIT For full moon nights.

      Choose the image that is closest in lunar phase to the lunar phase of today.

      Download the image to the desktop and process as described in Appendix G.

      The ordinary windows image opener will NOT work.

    21. And that is all for the Startup Presentation.

      If the C8 telescopes are available, we could all troop to the roof to do our Moon maps.

      If not, we can get to work on the inside parts of the lab.

  4. Short Definitions

    5. Some definitions of     Moon related words are hard to find in short form.

    I've provided some short or shortish definitions below.

    Boris Karloff, The Mummy

  5. Post Mortem

    6. Below are some generic comments for     Lab 12: Stellar Spectra that may often apply.

    Any that are semester-section-specific will have to added as needed.

    1. The Startup Presentation gives good definitions for this lab.

      Find them and abbreviate as needed.

      Don't just google for a word and take the first definition that you can find.

      Usually, it's just from an online dictionary written by someone (a lexicographer) who has copied and abbreviated unintelligently from some other source. Heck

    2. Answer questions that require sentences with sentences. Usually it is obvious what those questions are. Sometimes maybe not. Err on the side yes sentences are needed.

      Sentences begin with a capital letter letter and end with a period. Usually there is a subject and a verb. Not always.

      Since you are working in groups, you should have different group members read over the sentence answers to see if they are correct and comprehensible. Read them out loud.