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Ad Astra

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Everything posted by Ad Astra

  1. Celestial mechanics is often a difficult topic to teach - and to understand! But this activity will help you out a lot. It is also very simple, requiring only a ruler and a clock. The essence of the lab relies upon the fact that almost all adults have about the same reach - and that a ruler held at arm's length shows 1 cm = 1 degree in the sky. While this isn't perfect, it works well enough for most people. The idea here is to measure the Moon's distance from the horizon in degrees several times before moonset; then use the distance traveled and time taken to find the Moon's speed as it travels across the skies. My students will compare their results to the Earth's rotational speed (0.25 degrees per minute) and the Moon's orbital speed (0.009 degrees per minute). You should find that your own results are a lot closer to the first answer than the second - proving that most of what you see at Moonset is the Earth's rotation, not the Moon's orbital motion! Let me know how you get on! Dan Tracking Lunar speed.doc
  2. Hello Jeriah, I use a lot of Orion equipment (I'm and astronomy instructor), and I have 12 Orion dobsonians in service. The 8" is a super scope and will serve you well for years. These scopes are exactly what my students all learn astronomy on - I recommend them highly. You will find them rugged, easy to set up and use and the views are fantastic - especially for the price you pay. As for the intelliscope, I'm not exactly a fan. They do work, but a computerized mount without the ability to track just isn't my style. I find them a lot more trouble than they are worth - especially as you say that you already know the sky fairly well. I would be you would get a lot more use and enjoyment if you put the difference in price into some nice eyepieces or accessories. Dan
  3. Here is a scan of the M-13 lab as done by one of my high school students. This lad had never used a telescope or binocular before a few weeks ago. Dan M-13 Sample.doc
  4. This one is for the early birds. The moon has been showing off as it moves across the sky, over the weekend, it will run past Jupiter, then next weekend, it will run past Venus. This is a chance to see the celestial motion of a body in orbit for yourself. The activity is easy enough, just pencil and paper, or go out and have a look. I am asking students to use Orion as a yardstick to approximate the actual travel of the Moon through the skies. Across the top (Betelgeuse to Belatrix) is about 8-degrees, from Beletrix down to Rigel (Orion's right side) is 15 degrees, and across the belt is about 3 degrees. Comparing distances to these will help you get a feel for how big the sky is - and how large some of these constellations are. When you sketch the sky for the Moon's pass by Venus, you will find the sky too bright for seeing constellations. Note the Moon's position relative to the horizon each morning from the 10th - 13th. If you divide the 360-degree orbit by the 27.3 day orbital period of the Moon, you get an average daily motion of just over 13 degrees per day. How does this agree with what you see of the Moon's movement? Don't delay! If you miss this pass, you will have to wait a month to see it again in early November! Let me know how you get on! Dan Tracking Lunar Motion.pdf
  5. Quite a nice shot for a first attempt! Congratulations, Nebula. You get an A on this lab from Dr. Barth! Dan
  6. We had 80 people out in the Astronomy Stadium (I let the football blokes paint silly stripes all over my field and use it during the day... ). All of us were hunting down the elusive M-13 - and doing a bang up job of it, too. Everyone was able to find this object easily enough, and telescope skills are getting better all the time. I was using my GLP to show how to hop from Draco to Hercules to Corona Borealis when one kid asks: 'Where's Ursa Major?' When I pointed out that it was mostly behind the hills at our site, I heard a comment come out of the dark: "Drat! Just when I start to learn where things are, the stars move!" Glad you are enjoying it. Watch for the next lab - "Make a Photo/Map of the Moon!" Dan
  7. Hi Folks, Hercules is high in the sky and easy to spot - that means it is time for hunting globulars! Globular clusters can contain up to a million stars, all tightly bound together by mutual gravitation. These clusters tend to form a loose shell or halo around most galaxies - thus they are the most distant thing we can see within our own galaxy. Try this one out and let us know how you do. Dan M-13 Cluster in Hercules.doc
  8. Hello friends, I think I must have expressed myself badly again. Let me try to clarify, if I can. My students are studying the Moon just now, and we will discuss theories of the Moon's origin, and evidence for and against those theories. Every theory must account for the evolution of the lunar surface over time (billions of years of time with the rate of impacts decaying much as half-life decay affects a radioactive sample). Because there is no air or water on the lunar surface, you can see evidence of changes in the surface quite clearly even though the actual event occured billions of years in the past. One has to remember that the model for lunar geologic change is a catastrophic model - not a gradualism. Change here occurs in sudden, violent bursts, followed by long periods of almost perfect preservation of the status quo. Here are some samples of geological change that you CAN spot and appreciate on the Moon with a modest (150mm dob) telescope or better. 1. Crater deformation. Craters begin life as narrow, conical depressions, but severe stresses in the crust cause this structure to quickly collapse - steep walls slide inward and the crater basin fills and levels with debris. Late crater wall collapse can be seen and evidence of large blocks of basalt from the rim sliding and pushing a rubble field ahead of them which fans out on to the crater floor. Lava filled craters like Plato show this sort of phenomena very clearly. 2. Lava flooding, and flood sequencing. Craters which border maria often show evendence of rims that are overwhelmed by lava flooding from the maria. Sometimes if the local solar angle is low enough, you can even see ripple structures which clearly evidence the direction of flow. Ripples from a small source (like a crater wall breach) show characteristic bow-like structure as the liquid wave front spreads out from a narrow source to a wide area. Lava colour and flow lines often make it clear which flow happened first, even if we cannot definiatively date them from the eyepiece. 3. Crater saturation, crater erosion. Especially in the highlands of the southern lunar hemisphere, you can see evidence of ancient crater basins that have been overwhelmed by subsequent (generally smaller) impacts. A good map is needed here, and you must choose the day (and local solar angle) carefully, but ancient structures can be revealed - and at the same time the scale of impact and bombardment can be appreciated. 4. Central mounts in craters. A central mount occurs when an impactor punches deeply enough into the lunar interior to cause a rebound - effectlvely, the impact energy is sufficient to make the lunar surface act like a liquid for a very brief time. Look at a high speed photo or film of a water drop falling into a liquid surface and you will see much that resembles crater structure! It is instructive to compare central mounts in flooded craters (such as Gassendi) to those of unflooded craters (such as Tycho). There are many more examples - but these will serve to get you started, and help you to enjoy your views of the moon even more. Cheers, Dan
  9. Hi Big Jim, "One-Page-Easy" is part of the way I write curriculum for my classes. I've found that if I put an introduction, instructions, and a place for a response (data, sketching, etc) - and it still all fits on a single page, then I have made the lab simple enough, short enough, and easy enough that any begining astronomer could happily spend an evening enjoying the exercise, and a high school student could zip through the exercise in under an hour and still do a creditable job. When I post an activity here, I've usually already tried it out with my classes here in California. When I see what kind of success that my own students have, then I'm ready to release it (usually with a few tweaks and adjustments) to everyone on SGL. I'm very keenly aware that my students have an instructor to hand and can ask for help or clarification when they need it - the best you lot can do is post a reply or PM here and wait for an answer. As for your crater dilemma - that's just a matter of learning the lay of the land. Instead of trying to match your view to a map - try doing it the other way round. Look at your map and pick out 3-4 large and prominent craters, and then see if you can find them on the Moon. Once you get to know landmarks like Tycho, Copernicus, Gassendi, Clavius and a few others, you will start to be able to identify the smaller ones nearby by thier relationship to the larger, easier to find members. This way you also limit your task to a handful of large, easy targets - you're not trying to look through the eyepiece and identify everything you see (a much harder task!). One last thing, friend -- I think you vastly underrate both yourself, and the kids in both our countries. I teach in a relatively poor, rural community where most families are low income, many kids are still learning English, unemployment is pushing 25% locally, and many of our parents haven't finished high school themselves. Even so, the kids amaze me every day by what they are able to achieve when they are given a sufficient challenge to measure themselves against and proper guidance from the adults in their lives. If they can, then you can, too; and when you learn how, turn around and teach a child. Both of you will benefit immesurably. Cheers, Dan
  10. My students took this one on tonight with the gibbous moon. Tycho was clear and there was a wonderful view of Gassendi and mare Humorum. We had the C-11 out and the kids followed along on the 150p f/8 dobs and 7x50 bins. I will scan a few of the best and (with permission) post them here. They make a decent mark to shoot at, as none of them have been at astronomy for more than 5 weeks... and they have the added handicap of having me drone on at them for an hour a day! All of the kids found that translating what they were seeing into something comprehensible on the page to be very challenging. I have found however, that even simple sketching can be accurate and exciting, but it requires patience at the eyepiece, and some discipline in the act of observation. You cannot possibly record anything accurately if you do not trouble to observe it closely and accurately. It all amounts to practice - and if you LOVE IT like most of us do, this isn't onerous, it's heaven. For many students, astronomy becomes just another thing to learn to do like kicking a football or solving a quadratic equation. For me, as an astronomer; I want the kids to dig in and revel in the deep mystery and endless inquiry and discovery and the joy that transcends learning. But as a teacher, I have to cast a wider net than that. I have to challenge people like them (and you lot on SGL!), to dig in to the science a bit, but not forget that I'm here to inspire and create people with practical thinking skills. I have to engage and entertain, but keep focused on the fact that everything I do has to be relevant - hopefully relevant enough to help them get and keep a job after their done with school. What we do here on SGL is important. When I share lessons here, you folks help me hone and shape the curriculum, and I in turn, share it round the world with other teachers and parents. Generally, when things work well here, I know I can count on them in the classroom, too. When they don't (and sometimes the silence is deafening!), I know I've got to go back and rework the exercise. It's all good - in the end, you lot help me to be a better educator... and then the kids win, too. Thanks, Dan
  11. Hi Meg, so glad to hear you will be taking it out to the club - let me know how it goes! Dan
  12. Hi Folks, Waxing moon makes a lousy time to go looking for deep sky wonders, so let's concentrate on the lunar surface! For beginners, try the Lunar Sketching Activity. This will familiarize you with basic lunar maria and major features. For more experienced observers, try the Lunar Surface Features Activity. This second activity requires a small telescope and moderate power (60-120x); it challenges you to seek out 10 distinctive lunar features and display them in a series of just 3 sketches. You will have to search carefully to get all 10 in just three sketches! For those of you with camera - you can try the same activity - just see if you can get these 10 features in just three photos of the lunar surface! Let us know how you are doing - questions and comments always welcome. Dan First Sketch of Luna.doc Lunar Surface Features.doc
  13. With the Moon waxing this week, why not try your hand at really exploring some lunar craters along the terminator? (That's the line that seperates light from dark on the lunar surface.) Lunar craters can show a surprising variety of features and the craters themselves change as they age slowly over billions of years. Download the 'One-Page-Easy' activity and give it a shot. See if you can find, sketch, and then map the location of the features you observe. Bonus points for those who can later positively identify the features they've sketched using a lunar atlas! Give it a go and let us know how you do... Comments and questions are always welcome. Dan Lunar Crater Anatomy.doc
  14. My brother-in-law lives in Los Angeles and was good enough to send me these photos of the Space Shuttle Endeavor making its last flight into LAX airport. (Thanks Bill!!! ) The photos are lovely, and I've always found the Shuttle to be a wonderful machine, and I admire the astronaut core very greatly. But I readily admit to very mixed feelings here. My country had no real national service or day of mourning for Neil Armstrong - the first human being to set foot upon another world - and yet we are spending many weeks and loads of hoopla and news coverage of the last tour of a technology we no longer use. I try to imagine something similar in Britian.... Britian announces that all Navy ships will be retired - and simultaneously cancels the existing development program for all new ships. Then you lot spend weeks - towing mind you, not sailing! - you remaining ships around the UK so people could cheer things like "We used to be a seafaring nation! Hurrah!", and "Look what we used to be able to do! Hurrah!" Then you decommision your last ships and place them in permanent dry dock as monuments to your former glory. Meanwhile, there are no British sailors anywhere upon the waves, and no plan to put them there any time soon. Not only this, but the media and the government all cheer and tell the great UK public that this is a "Triumph of our Nation for the 21st Century!!!!". No, you see, I just can't quite imagine it. *sigh* Only in America. Anyway.... the photos are amazing and I hope you enjoy them. Dan
  15. Yes, I know it isn't the ideal time of year for Scorpio, but I tend to do things during the academic year and take time off in summer. The other option, of course, is to wait for Scorpio to be an early morning sight in late winter / early spring! Dan
  16. Quite right. If you don't see what you want, then it is time to ask your local dealer. Trust me, these folks live for this stuff. Tell them what you want and give them the challenge, I'm sure they can find (or put together) a package to suit you. This is where you really get your money's worth from the dealer's expertise - and you get just what you want in a telescope package. Dan
  17. I highly recommend the 150-P Dobsonian. I have 12 of them (really!) and all my astronomy students learn on this equipment. The perfect combination of excellent optics, light weight, portability, and optical performance. You would have to go a long way to find something better for the money. You are welcome to PM me if you have further questions. Dan
  18. It seems as though you need something a little more dust proof (and critter proof!) than just a dust sheet. If you are a DIY person, you might try what I did - making your own padded, zip-shut carry bag. I made mine from 'Celestron Orange' canvas (cotton duck cloth) - two layers of canvas with a layer of heat-reflecting curtain liner in-between. Total cost for a tripod bag, scope bag, and accessory bag was less than $25 (most of that was for the zippers!) It isn't what you would call pretty - but it does the job AND keeps the spiders and bugs out. We have both black widows and brown recluse spiders here in the desert, and I've found both of these poisonous bugs in and amongst my gear in the garage many times - ugh!!! No problems since my little sewing project, though! Cheers, Dan
  19. Hi Folks!, Scorpio is quickly fading into the west, but there is still time to try this double star challenge! The "claw region" of Scorpio is particularly rich in both actual and apparent (visual) double and multiple stars. Even a pair of simple 10x50 bins will reveal many of these targets, while others will challenge even more experienced observers. For the new telescope owner, this activity will offer several enjoyable evenings of activity as you learn to appreciate the wonders of the southern sky. Even experienced observers sometimes miss the beauty of double and multiple star systems as we go charging off in search of flashier nebulae and globular clusters - this is a chance to set the balance right! No less notable an astronomer than William Herschel confirmed the existence of true binary stars, and his sky survey in the late 1700's increased the number of known double stars from a few dozen to well over 800 -- not through miracle technology, but rather through skillful and patient observation! Here is your chance to follow in the footsteps of this famous English scientist! Let us know how you get on, won't you? Questions and comments are always welcome. Dan MoM - Double Stars in Scorpio.doc
  20. I worked for Scope City for almost 7 years. The company is legit and has been around for at least 30 years. Prices are generally competative and they will often match what someone else advertizes (at least they used to...). They are also very hard-nosed about returns. They used to only offer credit or exchange, not refunds! Mail order may be different, but check with them on this before you order. If the price is good and you know what you want, I wouldn't have any hesitation in recommending them. Dan
  21. I have spoken with some of the folks at Funderstanding.com about doing a 'How to Sketch the Moon' video. If I can get someone to produce it - I will post it here. The actual clock method activity sheet is attached for eveyone - sorry, should have attached that earlier. Like all the activities,it is "One-Page-Easy" and this one has circles pre-marked with 'hour lines' to help you practice sketching. I hope you all enjoy it! Dan Lab Skills - Sketching with the Clock Method.doc
  22. Many of my students shy away from sketching. "I have a camera for that!" and "I'm not an artist!" are often heard in the classroom. Even so, most people find that with a little practice, they can make a creditable sketch of lunar features. Sketching is very pleasing and gives us a record to take away from the eyepiece after a long night of observing. We use a technique that I call the "Clock Method". --> Imagine that the lunar surface is a clock face. --> Start at 12:00. Add in only the general shapes. --> Keep an eye on: a) how large the feature is How far from the center it is c) How the size compared to other nearby features. Work your way around the clock, hour by hour, and you should have a very creditable sketch. How do you know if you've succeeded? Check your drawing against a photo or atlas of the Moon. How many features you have drawn can be positively identified? I've attached a couple of lunar sketches I've put together from those submitted to me in class. None of these students have had astronomy before, and they have been with me only a few weeks. If they can do it - so can you! Dan Lunar Sketches.doc Lab Skills - Sketching with the Clock Method.doc
  23. Thrilled to see almost 100 downloads on this one! I took my 4 astronomy classes out last night to look at Lyra. We had over 80 people out on the astronomy pitch (formerly known as the "football stadium"). It was quite lovely and we had a family of coyotes serenading us through most of the eveing with yips and howls. Really added quite the 'Old West' feel to our outing! Dan
  24. I would suggest Lyra. You have the double-double (epsilon-Lyrae), a nice open cluster centered on the star Sulafat (southernmost corner of the parallelogram that makes up Lyra), the Ring nebula (between Sheliak and Sulafat), and nearby is the globular cluster M-56. We were out last night doing the same activity with 80 of my astronomy students! You can find my Lyra activity <HERE>. Dan
  25. As we move into the waxing moon this week, we sometimes find ourselves grumbling that the increasing moonlight interferes with our observation of the deep sky. With the waxing moon, we get to see sunrise spread across the face of the lunar globe over the course of the days, and we can take this opportunity to use the low solar angle to reveal amazing geological features across the lunar surface. We all know that the lunar maria are large impact basins, roughly 3.2 - 4 billion years old, and that after the asteroids punctured the lunar surface, these great basins filled with lava over the millenia. It is still possible today, to see where different lava flows have broken out of their confining basins, where large crater rims have been besieged with lava flooding, and then given way. We can see the ripples and flow marks in the lava on the great basins today. Color also gives a clear indication of where one flow succeeded another. It is often possible to trace the history of an area geologically by looking for which lava flows are on top and which have been buried, overflowed, or otherwise obscured. For those with a dobsonian or other Alt-Az scope, this lab represents a great challenge. To sketch and to track at the same time with any Alt-Az telescope is very difficult. You will have to limit the maximum magnification in order to have reasonable time to sketch between moves of the telescope. For those with equitorial mounts, and especially those with telescopes capable of motorized or computerized tracking, this is just the challenge you've been waiting for. A chance to find an interesting target and then to study it without losing it out of the eyepiece. Your sketch can be at a higher magnification and may show fine details such as rilles and flow lines that the non-tracking scope simply cannot show without great difficulty. I will scan and post a couple nice drawings from my class this semester to show you all what can be accomplished at the eyepiece with a little practice. Comments and questions are always welcome. Cheers, Dan Lab #10 - Lunar Lava Flows.doc
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