mikemarotta

Well, we are getting away from the Moon here, but that point came out in one of my classes. Our professor was taking some other grad students to a project and the prof complained to me once that the driver relied on the GPS. (This was 2010.) And after several trips to the same place still did not know the route -- or apparently recognize it when they arrived. Ground truth. In geography, we call it "ground truth." And it applies here to astronomy with spectroscopy, etc. You can have "yellow." But is it a radiation, an absorption of colors not-yellow with reflection, or filtering? You don't know until you go there and get the ground truth.

With my ES 102mm f/.6.47 refractor my most versatile viewing is with the 17mm and 2x Barlow. I will go down to 8mm (skip the 13) to split a binary. The 6mm does not do much for me. Just sayin'.

In science, a good problem takes us far beyond the results of a single observation. The Christmas Star has been debated on many levels. The International Planetarium Society website (ww.ips-planetarium.org) lists over 100 citations to the Star of Bethlehem. Some of those articles and letters were part of a multifaceted decades-long argument among at least five astronomers and one editor. Writing in Archaeology Vol. 51, No. 6 (Nov/Dec 1998), Anthony F. Aveni cited 250 “major scholarly articles” about the Star of Bethlehem. For about 1500 years, the story of the Star of Bethlehem was accepted as historically accurate because it was divine truth. Miracles were not questioned. With the Renaissance, a new way of looking at the world evolved. Over the centuries, the Christmas Star has been explained as a comet, a meteor or meteor shower, but the conjunction theory has been the most popular. I have an entry on my own blog https://necessaryfacts.blogspot.com/2017/12/the-christmas-star.html and I publised a version of that in our local astronomy club newsletter the next year.

I have a National Geographic 70 mm and oculars ("eyepieces") in the same range. I saw features on Mars with 12mm and 2X Barlow. What I could not do was split all four stars in episolon Lyrae. I tried on three different nights. I can do it with my 102 mm refractor, not the 70. So, there's a limit to how much light you are gathering. But you should have no problems with Venus, Mars, Jupiter, and Saturn, the easy Messiers and binaries. As happy-kat recommends, get comfortable. Your eyes will see more. And most seeing is done with the brain. You will see 60 times more in 10 minutes than you will in 10 seconds.

Our local club interfaces with the area libraries - different political structures in the cities within the counties. We set up star parties, sometimes several in a week (pre-Covid). But we have not donated telescopes. I will mention it to the executive committee next month. Thanks. Mike M. Vice President, Austin Astronomical Society.

Obviously, you want to clean it without damaging the coatings. I cannot help. However, I do want to thank you for mentioning the Williams Optic brand. I had no idea that they exist. I went to their website. I am impressed. In our local club, if someone in the public community turns to us for our outreach people just echo the most common brand names. I am not sure that we are doing a service. I am going to recommend to the executive committee that we think about a standard reply with a broader range of vetted details. Be that as it may, thanks again, and good luck. You have an outstanding instrument that deserves the best care. Mike M.

I had no idea. Thanks for the tip. I bookmarked it. Mike M.

I love the contour lines. I have several maps of the Moon. None with lines. I had a couple of classes in geography and geographic information systems as a graduate student. I also had map-reading classes in the military. It just never clicked with me that a map of the Moon needs the same vocabulary. Thanks.

Welcome. Any telescope is better than no telescope. Galileo changed a civilizaton with an instrument one-tenth of yours, more for the clarity of your glass than the mere power of magnification. You can get some good opinions here if you take it all with a grain of salt. You seem to have a good, basic instrument. I have a ten-inch in the garage and use my 70-mm far more often. My preferred telescope is 102 mm and an f/6.47. I like the 70-mm because it is an f/10. You have an f/9 focal ratio (700/76 = 9.2) which gives you good potential for more magnification when you want it. Also, you have a good range of eyepieces ("oculars"). You will find that your Barlow and the 1.5 erecting will give the other eyepieces some extra (serviceable) power. Usually, wider views are better than stronger ones, but it depends. With your telescope, you ought to be able to see the rings of Saturn and the moons of Jupiter and enjoy the close conjunction. The Moon will become a familiar neighbor. Mars will be a disk. You might make out some shading. You can find a list of easy and attractive binary stars to pursue, such as Albireo, the Foot of the Cross or the Head of the Swan, a stunning pair. There are others, easy and with color contrast. If you go out an hour a month, at the end of a year, you are like at lunch on your second day on a new job. It is a learning curve. If you find this fascinating (as we all do), then your first telescope will not be your last. Your local library will have books. The books will explain to you want you are looking at. I mean, just for instance, the Andromeda Galaxy is an easy target. But it will not look like it does in a television show. Nonetheless, when you spot it and view it and consider what you have found, you cannot help but be inspired by your own achievement. Best Regards, Mike M. Vice President, Austin Astronomical Society mike49mercury@gmail.com STELLAE AVTEM HARENAE.

I like this because it is an honest product from another amateur. I am distrustful of processed images. I am solidly supportive of the methods and means by which "everyday people" like us explore the extra-terrestrial universe. I believe that science is for everyone who wants to practice it. What would make it perfect would be a write-up explaining the image. I mean, I assume the the stars in the middle of the whirlpool are between us and it. But how do you know? You do say a bit about equipment, instrumentation, calibrations. (42 x 2 minutes Evostar 100ed + 0.85 reducer ASI294MC Pro -10 gain 120.HEQ5 Pro AsiAir - guided) That is nice for your mates who know what all that means. Myself, you have a refractor with extra-low dispersion glass, a form of apochromatic correction. You took 42 snapshot in two minutes. You used a "reducer" which is the opposite of a Barlow lens. I have no idea why you would, but I see that you did. Whether your gain of 10 is a lot or a little depends on the range of your rheostat (varistor, volume control). The rest is lost on me. I only ask because I usually pass over all of the tarted-up airbrushed pinups posted here and on every other discussion board. Your image seemed honest enough. It sent me out to read about M81. I have something new to pursue. So, thanks, again. The thing is that I work as a technical writer. You take a picture. I write 1000 words: https://necessaryfacts.blogspot.com/2018/12/the-andromeda-galaxy.html Best Regards, MIke M.

Our local club lends telescopes to members. The program has several goals, one of which is to give people the opportunity to try out different instruments and configurations. It is also true that the club's inventory is pretty much aligned on Dobsonians, 6 to 12-inch (150 to 300 mm) and above when we can. Everyone likes dobs. As an officer I defer on first choice and take whatever is around; and right now, I have a Meade 10-inch "Advanced Ritchey Chretien." That is in quotes because - as I found out from some googling - the design is not truly an RC. The Ritchey-Chretien has two hyperboloids. This arrangement is different than that with the typical Schmidt-Cassegrain lens alleviating the compromises. The primary is a paraboloid and the secondary is a hyperboloid and the corrector plate makes up for the primary. I have about a dozen printouts about suits at law over the telescope. Meade at first claimed that it was the same design as the Hubble space telescope. They responded with the adjective "Advanced" to modify their advertising. I have not had an opportunity to use it yet. The weather is not cooperating. I would like to have three clear nights in a row because it is such a bear to set up. My previous loaner was a 10-inch Schmidt-Cassegrain that I used once and has been in my garage since April. I finally got the equipment chair to take it back. All he had in place of it was this other behemoth. My goal here is just to do some different kinds of observing from my backyard.

The local club that I belong to posts these four under the Frequently Asked Questions tab. Astronomy magazine Telescopes 101 http://www.astronomy.com/observing/equipment-use/2014/04/telescopes-101 Sky & Telescope Choosing Your First http://www.skyandtelescope.com/equipment/basics/12511616.html The Heretic's Guide to Your First Telescope http://www.findascope.com/ Ed Ting's Advice http://www.scopereviews.com/begin.html Above a certain basic level, like GBP 100 or USD 129, almost any telescope is better than no telescope. The thing to manage is understanding what you get for the money.

I am pretty happy with my ES First Light 102 purchased this October, but, yes, faffing was called for. I put two rubber strips under the objective because it so easily bangs down on the mount if you remove a big ocular.

13 December 2020 1815 hrs CST (UTC -6). Location = Austin., Texas 30.177276 North by -97.8044841 West. My goal was to sketch the present state of the Jupiter-Saturn conjunction. I calculted the Field of View and created a proportional workspace in my notebook. I already practiced viewing a ruler while viewing the sky with both eyes open. FOV = 2.42 deg = 145.45 arc minutes. Objective = 102 mm; Focal = 660 mm; F/6.47. Ocular 32 mm In this sketch line AC, the radius of workspace is 4.84 cm.

Welcome to the sight. You have a nice telescope for getting introduced to the skies.

Thank you, sir. (I feel as though I should salute.) I do have an interest, so "gain" is not quite the verb, though "enhance", "improve", "extend", and "expand" would all work. So far, it has been interesting and rewarding. I appreciate the work of the hosts and moderators.

Welcome, Neighbor. The National Geography 114 mm reflector is a good instrument. Of course, your new 8-inch Dobsonian and even the 130mm reflector will gather more light for you. The stars are not going to get amazingly bigger. The advantages will be in what the larger telescopes will reveal in deep sky objects and close-ups of the planets. Before you buy much more stuff, visit this board and some others and ask around. You will get a lot of opinons, often contradictory, though as a group, they will help steer you clear of choices you might not otherwise have made. The markets here are small. So, above some basic floor, there is no junk. That said, though, little more money or a different manufacturer or an alternate pairing might deliver for you an experience more aligned to your expectations. Allen is in the suburbs. How far are you from Connemara or a similar dark sky site? Have you found your local astronomy club yet: https://www.go-astronomy.com/astro-clubs-state.php?State=TX And what books do you have? (When entering new territory, it always helps to have a native guide.) Our local club brings us an automatic membership in the Astronomical League. Some folks here are hot in pursuit of long lists of targets. Myself, I am not. That said, though, the AL lists of targets do show you what is available and what can be fun and rewarding. It is easy to talk of nebulas and galaxies and there's lots of those among the many other interesting bodies.

Welcome, Pard. You will find maybe half a dozen discussion boards around. They all seem to be international. Astronomy is small group. The global marketplace has been variously estimated to be between $125 and $250 million, about a tenth of anything comparable such as coin collecting or sports equipment and miniscule compared to cosmetics. So, we all get to know each other over time. You have an impressive arrary of telescopes for a self-defined beginner. I look forward to reading your reports. Best Regards, MIke M.

Welcome. As you can see, I've been through the cool usernames. I look forward to reading your continued reports. The American sociologist Robert King Merton was born Meyer Robert Schkolnick. He took the name "King Merton" when he was a young teen performing stage magic and quickly found that "Merlins" were plentiful. (https://en.wikipedia.org/wiki/Robert_K._Merton).

Yes, actually, I received similar comments on a different board (The Star Searchers). I am not dismayed. The glass is good. It just does not meet my needs and I do have other instruments that it might be a better match for. So, thanks.

Watching this on DVD with the captions on allowed me to identify an array of failures of science, reason, and fact. The curtain opened with a quote from Carl Sagan: “The cosmos is all that is or ever was or ever will be.” The rest of the series denies that and betrays Sagan’s legacy with frequent allusions to “alternate universes” and “alternate realities.” But those do not exist except as subsets of the universe: all that ever was, is, or will be. That was Carl Sagan’s worldview; and it is the metaphysics and epistemology of rational-empiricism which is the scientific method. But the scientific method is not applied in this series while vague assertions and imaginative claims are touted as “great mysteries” and even “miracles.” The failure to adhere to the scientific method led to a cascade of ignorant statements about evolution and the origin of species. Contrary to the narrative of how wolves and humans learned to get along (Episode 2: Some of the Things that Molecules Do), the fact is that crosses of wolves and dogs can produce fertile offspring. They are not species as Darwin defined them. Neither are polar bears. Discussing the life and work of Sir Isaac Newton, (Episode 3: When Knowledge Conquered Fear) Dr. Tyson never mentions the fact that Newton’s theory of gravity—powerful as it was in defining not just a branch of science, but the worldview of a civilization—cannot be extended beyond two bodies in empty space. Any 3-body or n-body problem can only be solved for specially restricted cases or by repetitive numerical methods and reliance on compiled tables of direct observations. If you stop to read the words and reflect on the content, you realize that there is at once more and less here than meets the eyes and ears. That is a message from the opening of Episode 6: Deeper and Deeper Still, and it is presented in a way that denies the legacy of Carl Sagan. Dr. Tyson says: “Seeing is not believing. Our senses deceive us. Even the stars are not what they appear to be. The cosmos as revealed by science is stranger than we ever could have imagined. Light, and time, and space, and gravity conspire to create realities which lie beyond human experience.” But discovering the cosmos is the human experience. Epistemology, psychology, and physiology all inform us that our senses are accurate and precise. Why are the senses of bees, birds, and beavers reliable for them, but ours are specially cursed? Like them all, we, too, evolved on Earth and adapted to its changing environments. Our senses are in and of the world. Moreover, we invent and construct transducers – telescopes, microscopes, electroscopes, spectroscopes – that extend and enhance our senses. Would you suggest that the rings of Saturn and the nucleus of a paramecium are not real? We fail ourselves with bad ideas that deny the evidence delivered by our senses. The scientific method unites the rational and experiential, the theoretical and practical, the synthetic and analytic. Physical reality does not plot against us. We are in and of the universe. That was Carl Sagan’s message from the very beginning. Episode 14: The Immortals includes several errors across the curriculum of general science. Attempting to explain that we are broadcasting messages into the cosmos, Dr. Tyson offers Project Diana, an effort of the US Army Signal Lab to reflect radar with the Moon as the target. However, our electrical signals were already going out for a hundred years because just closing and opening the DC circuits of telegraphs from the 1840s caused electro-magnetic pulses. And radio transmissions began in the next generation. Anyone who knows the work of Carl Sagan knows that Contact gave the honor of the first the television broadcast into outer space to the opening of the 1936 Olympics. As for Project Diana, contrary to the cartoon, the radar signals from the Earth station did not go sweeping past the Moon. They were targeted to be as close to a lunar diameter as possible in order to maximize the return signal. Most of that, about 95% of the reflection, was scattered into space. But that is not what we were shown. Dr. Tyson’s script had him say that the civilizations of 2200 BCE all collapsed because of a worldwide drought. It was easy to claim in 2014. By 2018 that event was arguable. (Read about the Meghalayan debate.) Even so, the script says that among the civilizations that collapsed in 2200 BCE was that of Greece, but Greece had no such civilization then. The main point of Episode 14 was that life on Earth could have originated with entities in meteorites. But where did those organisms come from? Cosmos says that they evolved on other planets and were hurled into space by asteroid impacts on those alien worlds. But, then where did they come from? We have an infinite chain of antecedents. The fact is that long polyaromatic hydrocarbons (PAHs) such as naphthalene (C10H8) and anthracene (C14H10), are known to exist in nebulae. Dr. Tyson’s script correctly identified carbon as the key to life on Earth. And carbon seems plentiful in free space. Dr. Tyson says that bacteria from outer space are constantly and continuously landing on Earth in meteorites. He suggests that perhaps all life on Earth evolved from such bacteria. But they are fairly complex lifeforms. How could simpler life have devolved from them? If you stop and think about it, was it those alien organisms and not their host asteroids that eradicated life on Earth in massive extinctions? That possibility suggested by their premise seems not to have occurred to Ann Druyan and Steven Soter who wrote the scripts that Neil Degrasse Tyson spoke to us. (This review originally appeared on my blog, NecessaryFacts for 17 May 2020 as "Cosmos: A Spacetime Travesty.")

I got about halfway through this before taking up the edX class from EPFL (see topic here). The work was engaging. The explanations are clear, concise, and helpful. The book is supported by a website which supplies all of the problems worked out as well as recorded lectures. I had three college classes in astronomy (long ago) and I have done a fair bit of teaching in business, industry, and hobbies. I did demonstrations in chemistry and physics for a year for the Ann Arbor (Michigan, USA) Hands-On Museum. Before that I taught technical writing at my community college.) So, I really looked hard at their text and I was impressed. The Mathematics of Astronomy by Daniel Fleisch and Julia Kregenow, Cambridge University Press, 2013. Fundamentals: Units, conversions, scientific notation. Gravity: Kepler, Newton. Light: spectrum, radiation, Doppler shift, radial velocity. Parallax: angular size, angular resolution. Stars: stellar parallax, luminosity, H-R Diagram. Black Holes: density, escape speed, expansion of the Universe.

I worked through Astronomy Activity and Laboratory Manual by Alan W. Hirshfeld. The arithmetic, algebra, and trigonometry are easy, but real the fun is in following the logic and discoveries of the Paleolithic people, Aristarchus, Copernicus, and Kepler, up through Hubble, to measure the day, the distances to the Sun, the Moon, the planets, and beyond. Astronomy Activity and Laboratory Manual by Alan W. Hirshfeld, Jones and Bartlett Publishers, Sudbury MA 01776, First Edition. 2009, Second Edition 2018. This guide to hands-on learning instilled me with a sense of confidence about my ability to perform the basic mathematics of astronomy. The exercises start with measuring shadows to track the sun as evidenced by stone age monuments. Before the last one, the learner estimates the expansion rate of the universe according to Hubble’s Law. The learning does not end there. Prof. Hirshfeld is a good instructor, and the assignments come full circle. Having started with the Sun and Moon, the book ends by assigning the calculations to estimate the relative masses of Sirius and its dwarf companion. (Just to note: This is from the first edition of the book (2009); the second edition (2018) is a bit different; and a third edition is promised.) The stars are pretty at any magnification. It is most important to understand what you are looking at. Following these structured exercises, I gained an intuitive understanding of how astronomy developed historically, and (more importantly) of my location in the universe. It starts with the gnomon, basically a vertical stick in the ground. At the end of the shadow, you place a stone. In Chapter 2, several thousand years or generations later, you come to the conclusion that the angle of the Sun in the sky at mid-day is directly related to the length of the shadow relative to the height of the stick. Theta equals arctan(L over H). Hirshfeld provides good, simple explanations of the math, though not in depth. At the back is a tutorial on basic trigonometry. Neither is a substitute for a semester of trig. Hirshfeld just gives you the number 57.3 without telling you where it came from. Similarly, it is true that although you do not need much mathematics to benefit from the hands-on calculations, you do need some. Even so, Hirshfeld steps you through work that you will come back to again. The same basic formulas are applied repeatedly to new problems from measuring the diameter of the Earth to measuring the distances to the Moon and Sun and then to the stars. Even if you are completely math-phobic, you can still get a lot out this by at least reading through the exercises to appreciate how the Greeks, Galileo, Kepler, Newton, and the astronomers of the 19th and 20th centuries came to their conclusions. If all of the arithmetic and algebra is “digital” then “Activity 15: Picturing the Universe—How Photography Revolutionized Astronomy” is “analog.” I put off the central activity of “Activity 12: Parallax” until I finished the rest of the book. I could have just worked through it on paper, but I wanted to set up a yardstick in the doorway between the kitchen and the living room in order to take my own measurements. Alan Hirshfeld is the author of Parallax: The Race to Measure the Cosmos; W. H. Freeman & Co., 2001. So, I wanted to give him his due and take my time with the work before reading the book. Activity 1 The World's First Skywatcher - YOU! Activity 2 Shadowland Activity 3 Shadowland - the Sequel Activity 4 Shadowland Follow-up Activity 5 The Phases of the Moon Activity 6 Eratosthenes Measures the Earth Activity 7 Aristarchus Measures the Size and Distance of the Moon Activity 8 Aristarchus Measures the Size and Distance of the Sun Activity 9 The Copernican Cosmos Activity 10 Kepler's Third Law Activity 11 Isaac Newton and the Moon Activity 12 Galileo Measures a Mountain - on the Moon! Activity 13 Precision Astronomy After Galileo - Stellar Aberration Activity 14 Precision Astronomy After Galileo - Stellar Parallax Activity 15 Picturing the Universe - How Photography Revolutionized Astronomy Activity 16 How Bright is That Star? A Tutorial on the Magnitude System Activity 17 The Realm of the Spiral Nebulae Activity 18 Hubble's Law - in the Kitchen and in the Universe Activity 19 The Herzsprung-Russell Diagram Activity 20 Binary Stars and Stellar Motions. Appendix Mathbits In the second edition, Activity 19 is about Dark Matter. In fact, while I found the second half the H-R Diagram helpful, the introduction about height and shoes sizes was obvious. Perhaps plotting the land speeds and weights of various mammals would have been more analogous to the relationships between spectral types and luminosities. The second edition also replaced the work on Sirius A Sirius B with a your own reflective essay. I believe that was a loss. Although I have a calculator on my iPhone and my computer, I bought a new one just for this, a basic scientific TI-30Xa. It was $8.95 which is like 89 cents in 1978 dollars when we bought our first TI-30 calculators. The universe may not be expanding, but the money supply is. Still, I worked several of these in my head by approximation, 3 for pi and so on.

https://www.edx.org I signed up for the Introduction to Astrophysics from the Ecole Polytechnique Federale Lausanne. It is a short 7-week class. When I complete that, I will take on the larger and deeper challenge from Australia National University. What you'll learn Influence of gravity on celestial bodies Matter-radiation interactions Star formation and evolution Basics of cosmology I found the first two sessions easy enough. Session three is on statistical mechanics of globular clusters. I had to google for Virial Mechanics. Now the learning begins. I have worked through some other self-teaching guides from books. I paid for the certification for this course.

Thanks. I have nowhere near the complete list. In addition to Surely You're Joking and What Do You Care, I have the Easy and Not-so-Easy Pieces, The Character of Physical Law, and the Lost Lecture. Here' the story, though. I knew about Feynman from a classmate in high school physics (1967) and often saw the 3-volume set in bookstores, but never had the means or motive to buy them. But I did browse... Along comes the wife and then the baby... When the kidlet was about five or six, Surely You're Joking came out in paperback and was new in the store. I read a few pages and decided that it was perfect for bedtime stories. I mean, we did the usual Grimm's stuff and Barenstain Bears and Winnie-the-Pooh, but also Edith Hamilton's Mythology. The story of Feynman fixing radios was ideal. I did have to start it twice to overcome the objections to science at bedtime, but it got her hooked and we read that and What Do You Care when it was published. Fast foward 30 years and I got her the graphic novel.