I: GENERAL

1. Star wheel is for beginners, the next step is using star map or star atlas for star gazing.
2. It is equilavent to road map in terrestial usage: Help to locate the celestial objects, also help to find other celestial objects. Eg: Big Dipper as star pointer.
3. Use celestial coordiante system: Right Ascension (R.A.) and Decliantion (Dec).
4. The celestial objects include stars, binaries, variables, clusters, nebulae, galaxies and etc.
5. There are four seasons skymaps, with the major constellations and stars, and more advanced skymaps, that include ALL the constellations. The advanced skymap includes most of the bright stars and celestial objects that are visible through small telescopes.
6. The constellations in the skpmap appear smaller than the ones in real sky

II: BRIEF HISTORY

1. 3000 B.C. - Nomad in Mesopotamia developed some ancient constellations, eg: Leo, Taurus.
2. 150 A.D. - Ptolemy catalogued 48 NORTHERN constellations, mostly have associated Greek mythology.
3. 16 to 18 cent. - Due to global voyages, add the constellations from southern sky.
4. 1928 A.D. - International Astronomical Union defined 88 constellations.
5. Other cultures also have thier own starmaps.

III: MAGNITUDE SYSTEM

1. Originate from Greek astronomer Hipparchus.
2. As a unit to measure stellar brightness.
3. Scale from 1.0 mag. to 6.0 mag.
4. 1.0 mag. = brightest star; 6.0 mag. = faintest star that human's eyes can see. Therefore bigger the magnitude, fainter the star.
5. 1.0 mag. star is 100 times brighter than 6.0 mag. star.
6. Some stars are brighter than 1.0 mag., then there are zero mag. stars and negative mag. stars. Eg: Sirius = -1.45 mag.
7. Vega is standard 0.0 mag. star.
8. Bigger the aperture of the telescope = Fainter the stars the telescope be able to detect.
9. In skymap, the size of the star's dot represent the magnitude of the star. Brighter the star, bigger the dot.
10. It is apperent magnitude, with symbol m; and their magnitude system is absolute magnitude, with symbol M.

IV: STAR NAME

1. The system of naming stars originated by J. Boyer (1600s).
2. Use Greek letters for the bright stars in a constellation.
3. The brightest star in the constellation is named as alpha, followed by the abbreviation of the constellation. Second brightest is assigned as beta and so on. Eg: alpha Lyr, beta Lyr, and etc.
4. After Greek letters, use alphabets and numbers. Eg; R Lyr, AF Cyg, 51 Peg, and etc.
5. Most of the bright stars have specific names. Eg: alpha CMa = Sirius, alpha Ori = Betelgeuse, alpha Lyr = Vega, and etc.
6. Chain of roots: Mesopotamia - ancient Greek - Roman empire - Islamic culture - Renaissance Europe - Modern time.
7. Examples - Arabic: Rigel. Latin: Polaris. Greek: Sirius.

V: CELESTIAL OBJECTS

1. The Sun, Moon, planets and comets are not labelled in most of the skymap. Given the celestial coordiante of these objects at particular date and time, they can be easily found.
2. Due to light pollution, the maximun magnitude of stars that can be seen from urban and suburban area is ~ 4 - 5 magnitude. Therefore, simple skymap like four season skymap has only the stars up to 4 mag., and more advanced skymap contained maximun 6.5 mag. stars.
3. Binary stars: 2 stars orbit with each other. Also known as Double star.
4. Variable stars: The brightness would change in time, from few days to few months.
5. Globular cluster: A dense grouping of old stars in spherical shape. Contains more than millions stars.
6. Open cluster: A loose group of stars, generally contains few hundred stars.
7. Nebula: The cloud and dust in interstellar space.
8. Galaxy: A massive system of stars held by gravity.

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