Astronomy Notes

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These notes were created by Nick Strobel for the introductory astronomy courses he taught. They are offered to the net as a resource in astronomy education. Feel free to use them in your own astronomy courses or talks. If you decide to copy these notes, he would appreciate it if you would leave this notice of authorship in the source.

Latest updates:

• A new document about the star of Bethlehem;
• references for evidence of the slowing of the Earth's rotation (see the naked eye astronomy notes below); and
• references and web links to learn more about lifezones and the search for extraterrestrial intelligence (see lifezones notes below).

Recent updates:

• A gallery of galaxy pictures (see galaxy notes below);
• A History of Science reference list (see History of Western Astronomy below);
• A gallery of nebulae pictures is still under construction (see interstellar medium notes below);
• The comet section in the solar system notes (below) is updated and includes some pictures.
• Also, each web document indicates now date of last revision at the end of the document.

Currently these notes cover: a brief overview of astronomy's place in the scientific endeavor, naked-eye astronomy, a history of astronomy and science, some philosophy of science, electromagnetic radiation, telescopes, magnitudes, determining properties of the stars, the Sun, fusion reactions, stellar structure, stellar evolution, the interstellar medium, the structure of the Milky Way galaxy, extra-galactic astronomy, cosmology, and extra-terrestrial life. I also have included documents I created for reading assignments: an essay on the scientific method and scientific truth, angular momentum examples, quick scientific notation review, and a long list of review questions to be used by my students in studying for their exams.

Each document has an index at the beginning to allow you to quickly find the section that interests you. All of the artwork was done on my NeXT machine at home. The images on the screen are GIF images and I have linked them to the original EPS image for those who want to enlarge them without pixellation effects (note that the images are simple line drawings so the EPS file is often smaller in size than the GIF). If you have comments about these notes, please email me. Postscript versions of these notes are available for anonymous ftp downloading. Latex versions of these notes are available upon request.

Contents:

1. Introduction and Naked-Eye Astronomy. I introduce astronomy's place in science, and give a feeling for the timescales involved. Then I discuss the celestial sphere, motions of the Sun (solar and sidereal days, time zones, equation of time, and seasons), motions of the Moon (phases, tides, eclipses), and planetary motions.

2. History and Philosophy of Western Astronomy. I focus on the rise of modern science in Europe, from the ancient Greeks to Isaac Newton. I also briefly discuss the four fundamental forces of nature and what makes gravity so important for astronomy.

3. Method for Finding Scientific Truth. Borrowing heavily from Pine's book ``Science and the Human Prospect'' I talk about the scientific method, correlations, problem of induction, positivism, levels of testimony, empiricism, models correspondence with reality. This was a reading assignment, not a lecture.

4. Electromagnetic Radiation (light). General properties of light, definition of frequency, spectrum, temperature. Light production: Continuous radiation, emission lines, absorption lines and the Bohr model for the atom.

5. Telescopes. Covers refractors, reflectors, light-gathering power, resolving power, magnification, and atmospheric distortion.

6. Determining Star Properties. Notes for the properties of stars and how we determine them. Things like distances to stars, their masses, radii, composition and speeds. Also HR diagram, spectral types, and spectroscopic parallax.

7. Magnitudes. Notes on the magnitude system used by astronomers. Includes discussion of the color index and it's relation to the temperature.

8. The Sun and Stellar Structure. This set of notes covers: The Sun, interiors of stars, and nuclear fusion. Parts of these notes will be in outline form to aid in distinguishing various concepts.

9. Stellar Evolution. This set of notes covers: stellar evolution and stellar remnants. Most of these notes will be in outline form to aid in distinguishing various concepts.

10. Interstellar Medium. Notes on dust and effects on starlight, H II regions, 21 cm radiation, mapping galactic structure, and molecular clouds.

11. Galaxies. This set of notes covers: the structure of our Galaxy, the characteristics of other galaxies and finding distances to other galaxies (this includes the distance-scale ladder). Most of these notes will be in outline form to aid in distinguishing various concepts. I now have a gallery of galaxy pictures of various types of galaxies.

12. The Milky Way Galaxy. A brief description of the bulge, stellar halo, disk and dark matter components of our Galaxy. Talks about where the metal-poor and metal-rich stars are to be found. Also discovering the Galaxy's shape using low-power binoculars. Includes a nice picture of the Milky Way viewed edge-on.

13. Cosmology. This set of notes covers cosmology. The distance-scale topic is dealt with in the Galaxies document. I discuss Olbers' Paradox, the cosmic microwave background radiation, the fate of the universe (open or closed), and dark matter.

14. Extra-terrestial Life. This set of notes by Nick Strobel covers: life zones, types of stars to focus the search for suitable planets, basic definitions of life, the kind of planet where we think life would likely arise, and finally the frequencies we use in the Search for Extra-terrestrial Intelligence (S.E.T.I.).

15. Solar System. This set of notes by Nick Strobel is an introduction to planetary science. I discuss planetary atmospheres (what determines if an atmosphere sticks around and the transport of energy), a comparison between the atmospheres of Earth, Venus, and Mars, magnetic fields (magnetic dynamo theory), meteorites, comets, and the formation of the solar system. There are links to three graphical descriptions of the concepts covered: the Earth-Venus-Mars comparison (a flowchart), the greenhouse effect and the UV dissociation of water, and a flowchart of the calculations involved in determining if an atmosphere sticks around for billions of years.

16. Angular Momentum in Astronomy. This is supplementary reading, not lecture notes. I define angular momentum and give several examples of angular momentum in astronomy: Kepler's second law of orbital motion, Earth-Moon system, rapidly spinning neutron stars, accretion disk in a binary system, and a collapsing galactic cloud.

17. Quick Scientific Notation Review. Supplementary reading, not lecture notes. Here's a quick run through of working with really BIG or really small numbers - scientific notation. I'm assuming that the student has had a lesson in scientific notation in the distant past and so knows what ten to the second power, ten to the minus sixth power, etc. means.

18. Review Questions. A long list of questions that will be answered over the course of the class. They give prospective students an idea of what is covered in an introductory astronomy class. Astronomy students can use these questions to study for their exams.

Still have a question?

Sci.Astro

SEDS

What was the Star of Bethlehem?

What's Happening Up There This Month?

1. Abrams Planetarium Sky Calendar. We've used this calendar in some of our introductory astronomy courses. The on-line version has only text while the paper version has a calendar with the important phenomena listed in the day blocks and a crude sky map on the reverse side. This web page gives a chronological list of events for the observer in the northern hemisphere (particularly for those at the same latitudes of the 48 contiguous states in the United States). Abrams Planetarium is at Michigan State University in East Lansing, Michigan.
2. Sky Events from Astronomy Magazine. This web page gives a brief narrative of where each of the planets will be in the sky this month. It also gives information about other celestial wonders visible to the naked eye or through a typical amateur astronomer's telescope.
3. Morehead Planetarium Sky Calendar. First a brief narrative description is given for each of the planets and other notable objects and then a calendar of events follows. Morehead Planetarium is at the University of North Carolina in Chapel Hill, North Carolina. This web page is text only.
4. Woodlands Observatory in Adelaide, South Australia has sky charts and a sky almanac for those ``down under''! Their Sky Chart requires a graphical browser. Their Sky Calendar comes in two forms, a graphical one that has cute icons at the bottom and a non-graphical one that has the same data tables without the icons. All of the events are in hard-to-understand text abbreviations so be sure to make a copy of the glossary of abbreviations at the top of the calendar page.

Astronomy News

Ron Baalke is the Information Man for Jet Propulsion Laboratory. He distributes a calendar of space missions and astronomical happenings at the JPL Calendar site. All of the major events for the space missions for the upcoming year (plus) are listed.

The American Institute of Physics distributes the Physics News Update every week. Occasionally there will be astronomy discoveries listed.

Buying and Using Telescopes and Accessories

Astronomy Magazine gives tips on buying the right telescope or binoculars for you or your child in their Observer's Guide. You'll also find information about the telescope accessories and astronomy software on the market.

David Lent has some good advice on Buying a Telescope for $500 or less. He discusses the parts of a telescope, the features to look for, and also which telescopes to avoid.

Sky Surveys

1. The Space Telescope Science Institute has created a Digitial Sky Survey for the public. You can find the coordinates (Right Ascension and Declination) of an object and a picture from their survey. The pictures are in FITS (Flexible Image Transport System) format (used by many professional astronomers) and GIF format.
2. Tom McGlynn has compiled surveys of the sky at 15 different wavelength bands (from gamma ray to radio) into a very nice tool called SkyView. You can enter either the coordinates of an object or simply its name and which wavelength bands you want and it will put together the pictures in either GIF or FITS format.

AstroEd

Other Introductory Astronomy Classes

1. Kevin Long's Introductory Astronomy Course. Kevin teaches at SUNY Brockport, NY.
2. John Wallin's Astronomy 105 and 106 courses. John Wallin teaches at George Mason University (Fairfax, VA).
3. Astronomy HyperText Book at the University of Oregon.
4. Toby Smith's Astronomy 150 (introductory planetary science) course at the University of Washington.
5. Bob Grabhorn, an astronomer at Indiana University at Bloomington, taught a summer astronomy course at The Evergreen State College in Olympia, WA and gathered his students' research projects and lecture notes into one place. This page contains some huge graphics images so it will take a while to bring up.

Galaxy and AstroWeb

Astronomy Research on the Web

You can always email me. My address is at the bottom of this page. Enjoy the skies and keep them dark!

Back to Strobel's home page.

See some of Strobel's research.

last updated 07 Dec 95