But if you could spin and throw a top far enough away from the Earth so that it would not meet with friction or resistance of any kind, it would go on spinning forever just like the planets.
How to Plot the Position of a Planet.—One of the tests which a Boy Scout must pass in order to obtain a merit badge for starcraft is to “plot on at least two nights per month for six months the positions of all naked eye planets between sundown and one hour thereafter. The plot of each planet shall contain at least three fixed stars with their names and designations, colors of planets and stars to be recorded by him.”
Now, by looking at your almanac under the head of Morning and Evening Stars you will find all the planets which are listed as Evening Stars, together with the dates when they can best be seen. From your almanac for 1915 you will learn that
Mercury is an evening star, and can be seen about Feb. 5, May 31 and September 27 in the west, just after sunset; that
Venus will be an evening star from September 12 for the rest of the year; that
Jupiter will be an evening star until February 24; after that a morning star until September 17, and then an evening star for the rest of the year, and that
Saturn will be an evening star until June 28.
The first thing to do is to find what constellation is on your meridian at 9 P. M. for the month that the planet you wish to plot is to be seen. This you can do by looking at the map of the stars shown in [Fig. 67]. You can see any of the stars or constellations on your meridian by looking for them at 9 o’clock P. M. on the months marked above them.
This done, consult your almanac and find out what time the Sun sets on the day that the planet you are looking for can be seen.
As an example let’s take Mercury, which the almanac says is an evening star about February 5, and which can be seen in the west just after sunset. The almanac will also tell you that the Sun sets on February 5 at 5 o’clock.