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
  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.)
  6. 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.)
  7. 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)
  8. 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)
  9. Distinguish between the final stages of small stars and massive stars – (small stars – White Dwarf, massive stars – Neutron / Pulsars, super-massive stars – Black Holes.)
  1. 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 -
  2. 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.)
  3. 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.
  4. 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,)
  5. 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.)
  6. 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.)
  7. 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.)
  8. 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.)
  9. 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.
  10. Define the Universe. (Space and everything that is in it. About 10 to 15 Billion years old.)

Key Vocabulary:H-R Diagram

NebulaApparent Magnitude

StarBig Bang Theory

SpectrographElectromagnetic Spectrum

Nuclear FusionSpectrum

SupernovaAbsolute Magnitude

Light yearsRed 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:

8(8)(A – D - astronomy

8(6)(A-C) – force & motion

8(5)(A, D, F) - chemistry