Short Questions about the Sky


  1. What is the main reason naked eye astronomy was easier in the past?

  2. What are two ancient uses of Astronomy?

  3. Why do we have seasons (summer and winter for example)?

  4. Why is it that the positions of the stars in the sky are different at the same time of night in different seasons?

  5. What is the chief difference between Ptolemy's and Copernicus' ideas for the arrangement of the solar system?

  6. For what scientific reason did the ancient Greeks favour Ptolemy's idea?

  7. What is the chief difference between Copernicus' and Kepler's ideas for the arrangement of the solar system?

  8. What was the key factor that allowed Kepler to be confident in his new ideas, compared to those of Ptolemy for example?

  9. Discuss in a few sentences what the church objected to in Galileo's ideas.
    (I am not looking for a specific answer here but your response must fit what we know about Galileo, his ideas and the church of the time).

  10. Newtons law of Gravity is more general when compared to Kepler's laws of motion."
    Discuss in a few sentences what I mean by general in the above sentence. In science a theory that is more general is usually considered better.
    Include an example of when Kepler's laws cannot be used but Newton's law can. (hint: Something simple and everyday will do.)


  1. List the qualities astronomers look for in an observing site. What are the pros and cons of space-based telescopes?

  2. Astronomers often choose very faint objects in the sky to study.
    In fact, "cutting edge" observational astronomy usually means studying the faintest objects.
    What is it that telescopes do that is really useful for studying faint objects?
    This particular advantage exists even if you are just looking through the telescope with your eyes.

Motions of the Sky

  1. Which declinations can be observed from the North Pole? the South Pole? the Equator? our latitude (47.6 degrees North)?
    Which right ascensions can be seen from the above locations each day?

  2. What is the latitude of the North Pole? Why is it impossible to give the longitude?

  3. How many "hands" would be needed to measure completely around the horizon?

  4. What range of azimuth would include all the locations on the horizon at which a star can rise? Would this question make sense at the North and South poles?

  5. How would the length of the solar day change if the Earth rotated in the opposite direction? (A diagram of the solar vs. sidereal day will be useful to you!)

  6. Suppose that the ecliptic and the celestial equator were not tilted with respect to each other. How would the azimuth of sunrise vary throughout the year? How would the length of day and night vary throughout the year?

Sun-Earth-Moon System

  1. You are an astronaut on the moon. You look into the sky, and see the Earth in its Full phase. What lunar phase is observed by people on Earth? What if you saw a first quarter Earth? New Earth? third quarter Earth? (A diagram of the lunar phases will help with this!)

  2. The speed of light is 300,000 kilometres per second. This number isn't easy to get a feel for but it's good it's so fast because it allows us to see things instantly on Earth without waiting for the light to arrive.
    The Sun is far enough away that light takes an appreciable time to travel to us. Assuming the sun is 150,000,000 kilometres away, how long would it take us to realize if the sun suddenly stopped shining?


  1. Assume that the Moon has oceans. What will the tides be like? How many high and low tides will occur in the course of a day?