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Astronomy Test - Study Guide
To prepare for the Astronomy Test you need to be able to do the following:
1. Investigate how spectrographs are used to analyze the elemental composition of the star. – (The stars
spectrum indicates: composition, movement (direction & speed), rotation, magnetic field, age,
temperature. Astronomers match the spectrum produced by the star light with the spectrums of
known elements here on earth to determine the composition of the star and can also determine
the star/galaxy movement by the shift in the spectral lines.)
2. Explain how stars are classified according to their main characteristics including size, temperature and
magnitude. (A stars age can be determined based on the H-R Diagram. Stars are grouped
according to their size, temperature and brightness. Normally, larger size = greater magnitude
and higher temperature. Exceptions: Giant stars collapsing to white dwarf = decrease in
magnitude with increase in temperature; Main Sequence stars growing into Giant stars =
increased magnitude with decrease in temperature at first, temperature then begins to
increase.)
3. Classify and interpret the characteristics (size, temperature, magnitude/luminosity) of stars according to
their placement on the H-R Diagram. (HR Diagram Gizmo at www.explorelearning.com)
4. Explain how stars vary in brightness in terms of apparent and absolute magnitude. (Apparent – how
bright star appears to be in the night star when viewed from earth, Absolute – how bright star
actually is. Have both types of magnitude since night sky does not reflect distance.)
5. Describe the life cycles of stars: (review drawing in notebook for small and large mass stars.)
 Explain how stars are formed and their stages – (all stars come from nebulas, gravity pulls
together increasing density and temperature. Nuclear fusion of Hydrogen atoms to
create Helium begins at 15 million 0 C releases energy in the form of heat and light – a
star is born. Newborn star is called a protostar.)
 Identify the factors that determine how long a star will last; - (initial mass of the star when
born determines what it will become. Larger the star the faster it moves through its life
cycle- small mass stars live longer- use fuel efficiently)
 Explain what happens to a star when it runs out of fuel – (small to medium size stars collapse
in size and begin to die – White dwarf then Black dwarf for stars the size of our Sun.
Large mass stars become neutron stars while extreme mass stars become black holes)
 Distinguish between the final stages of small stars and massive stars – (small stars – White
Dwarf, massive stars – Neutron / Pulsars, super-massive stars – Black Holes.)
6. Describe and classify galaxies according to their physical characteristics – spiral, elliptical, and
irregular. (Spiral – Normal Spiral has rounded center disc with arms spiraling out. Barred Spirals
central disc is flatten to a more rectangular shape with arms attached to the ends of the central
disc. Contain old, new stars and gas/dust. Elliptical – ball shaped, symmetrical with mirror
image if cut in half. Contain mostly old stars and little gas and dust. Irregular – no pattern in
shaped can be determined. Contain mostly young stars and lots of gas and dust. Age –
(youngest) Irregular  Spirals  Elliptical  Quasars? (these are the oldest) see http://amazingspace.org/resources/explorations/galaxies-galore/
7. Describe the formation of the Milky Way galaxy and the Solar System within it. (Milky Way is a barred
spiral galaxy located about the middle from the center of the Universe. Galaxy contains the
solar system that formed about 5 billion years ago and is about 30,000 light-years from the
center of the galaxy on a spiral arm.)
8. Recognize and describe the Big Bang Theory as the primary accepted theory for the formation of the
Universe and Solar System. (Galaxies formed by gravity pulling together dust and gases after the
Big Bang.
9. Describe the evidence for an expanding universe and explain how this supports the Big Bang Theory.
(Red Shift – supports Big Bang that galaxies are moving away,)
10. Define a light-year and be able to use it on a scale model – ISN: Galaxies on the Move. (it is the
distance light travels in one year – 9.5 trillion kilometers.)
11. Recognize the importance of the light-year as a convenient measure of distance in space. (Use to
indicate distances in space since it is so large.)
12. Calculate the time needed for information from distant objects in space to reach the Earth using the
speed of light as a unit of measure. (If a star is 25 light-years away from earth, then the light
reaching earth now took 25 years to arrive.)
13. Know the relative location of our solar system within the Milky Way galaxy. (Our Sun and solar
system are about 2/3rds the way out from the center of our galaxy on one of the spiral arms.)
14. Know that the sun is the only star in our solar system and one of billions of stars in our Milky Way
galaxy. It provides more energy to the earth than any other star in the universe because it is the
closest star to earth.
15. Define the Universe. (Space and everything that is in it. About 10 to 15 Billion years old.)
Key Vocabulary:
Nebula
Star
Spectrograph
Nuclear Fusion
Supernova
Light years
H-R Diagram
Apparent Magnitude
Big Bang Theory
Electromagnetic Spectrum
Spectrum
Absolute Magnitude
Red Shift/Blue Shift
DO YOU REMEMBER SECTION: Where an atom’s mass comes from, counting atoms, counting the
number of different elements, Balanced vs. Unbalanced equations, subscripts and coefficients,
reactants and products, calculating average speed and acceleration.
Force = mass x acceleration.
Speed = total distance / total time
Other helpful study tools:
http://www.cosmos4kids.com/
www.projectsharetexas.org
8(8)(A – D - astronomy
8(6)(A-C) – force & motion
8(5)(A, D, F) - chemistry