Expert: Tom Whiting - 12/6/2010

Question
How do we map the planet position we see on the sky onto
the two-dimensional paper ? At night we see a planet as
a dot on the sky. As time pass this dot will move to another
position. How do we map these positions onto a paper ?
Is there a computer program that can do this ? Thanks.

Answer
Hi Jay,
No, I'm afraid there are certain functions in this world that still require the old-fashioned analog viewpoint, using what we use to call a pencil and piece of paper or papyrus, where you have to get up off your rear-end, away from your computer, and do it yourself.  (Cutting the grass, shoveling the snow and knocking coconuts off of trees, are still some other hard-work, analog functions). Sorry.  If it makes you feel any better, I had to do the same thing with the planets and phases of the moon back in the 1950's (pre-computer days) for my First Class Boy Scout rank, and later, the astronomy merit badge toward the Eagle Scout award.
So what you do is, you print out the Zodiac constellations using your printer and paper... then you go outside at night and plot where the planets are and place a dot at their location on the paper. Then about once a week (planets don't move that fast)... you recheck the night sky and you'll see that the planets have moved very slightly, so you put a new dot on your paper sketch.  Do this for a few months, and you'll see the real planetary motion.
That is what the instructions are trying to get you to do, go outside at night, rather than just printing the entire process off, on your computer. The advantage being, you'll actually get to see the real planetary motion in the night sky relative to the fixed stars... the entire purpose of the experiment! I guess you can always 'cheat' with a computer, but then, you're the ultimate loser in that process, because you miss seeing the "real" event in the night sky.
Clear Skies,
Tom Whiting
Erie, PA USA