Astronomy 110 PRINT Name   __________________________
Fall 2005   Section 006   

Homework 2 : Where is?

(Due Thursday, Sep 8, 2005)

Some of the questions in this homework require you to indicate various answers on the diagram below, as well as giving reasons for your answer. You should therefore answer all the questions on a separate sheet of paper and you must attach the signed question sheet. Try to explain your answers as fully as possible. You must include an explanation to get a grade for the question.

  The skymap on the left shows an image of the sky over Honolulu on some day. The dots represent bright stars (if you could see them while the sun is up) and the names of constellations are given. Also shown are the positions of the Sun and planets if they happen to be in the particular direction shown; a key to these symbols is given below. The horizon is toward the bottom of the picture (though it may be out of the field of view of the picture). North is at the top and east is to the left (as with all skymaps).
--- Sun    --- Mercury
--- Venus   

One of the straight lines on the skymap represents the celestial equator and the other represents the ecliptic. You'll notice that one is marked off in hours of time and the other in degrees of arc; note that one hour of time is the same as 15 degrees of arc.Indicate on the picture which line is the equator and which is the ecliptic, and explain why.

Can you say what the date is, roughly, and explain why?

How many hours of sunlight will there be on this day? Explain why, and include a diagram.

Label roughly where you expect the Sun to be one week later, and explain why.

Suppose the tilt of the Earth's exis were to change from 23.5 degrees to 10 degrees. Draw on the skymap how the ecliptic would look in that case. What would be the latitudes of the arctic and antarctic circles? Explain. Would Honolulu still be in the tropics?