HOW TO FIND THE PLANETS

Other Worlds by Garrett Putman Serviss is part of the HackerNoon Books Series. You can jump to any chapter in this book here. HOW TO FIND THE PLANETS

HOW TO FIND THE PLANETS

There is no reason why everybody should not know the principal planets at sight nearly as well as everybody knows the moon. It only requires a little intelligent application to become acquainted with the other worlds that have been discussed in the foregoing chapters, and to be able to follow their courses through the sky and recognize them wherever they appear. No telescope, or any other instrument whatever, is required for the purpose. There is but one preliminary requirement, just as every branch of human knowledge presupposes its A B C. This is an acquaintance with the constellations and the principal stars—not a difficult thing to obtain.Almost everybody knows the "Great How to tell which planet it may be, it is the object of this chapter to show you. As an indispensable aid—unless you happen already to possess a complete star atlas on a larger scale—I have drawn the six charts of the zodiacal constellations and their neighbors that are included in this chapter.

Chart No. 1.—From Right Ascension 0 Hours to 4 Hours; Declination 30° North to 10° South.

Having learned to recognize the constellations and their chief stars on sight, one other step, an extremely easy one, remains to be taken before beginning your search for the planets—buy the American Ephemeris and Nautical Almanac for the current year. It is published under the direction of the United States Naval Observatory at Washington, and can be purchased for one dollar.This book, which may appear to you rather bulky and formidable for an almanac, contains hundreds of pages and scores of tables to which you need pay no attention. They are for navigators and astronomers, and are much more innocent than they look. The plain citizen, seeking only an introduction to the planets, can return their stare and pass by, without feeling in the least humiliated.

Chart No. 2.—From Right Ascension 4 Hours to 8 Hours; Declination 30° North to 10° South.

In the front part of the book, after the long calendar, and the tables relating to the sun and the moon, will be found about thirty pages of tables headed, in large black letters, with the names of the planets—Mercury, Venus, Mars, Jupiter, Saturn, etc. Two months are represented on each page, and opposite the number of each successive day of the month the position of the planet is given in hours, minutes, and seconds of right ascension, and degrees, minutes, and seconds of north and south declination, the sign + meaning north, and the sign − south. Do not trouble yourself with the seconds in either column, and take the minutes only when the number is large. The hours of right ascension and the degrees of declination are the main things to be noticed.Right ascension, by the way, expresses the distance of a celestial body, such as a star or a planet, east of the vernal equinox, or the first point of Aries, which is an arbitrary point on the equator of the heavens, which serves, like the meridian of Greenwich on the earth, as a starting-place for reckoning longitude. The entire circuit of the heavens along the equator is divided into twenty-four hours of right ascension, each hour covering 15° of space. If a planet then is in right ascension (usually printed for short R.A.) 0 h. 0 m. 0 s., it is on the meridian of the vernal equinox, or the celestial Greenwich; if it is in R.A. 1 h., it will be found 15° east of the vernal equinox, and so on.

Chart No. 3.—From Right Ascension 8 Hours to 12 Hours; Declination 30° North to 10° South.

Declination (printed D. or Dec.) expresses the distance of a celestial body north or south of the equator of the heavens.With these explanations we may proceed to find a planet by the aid of the Nautical Almanac and our charts. I take, for example, the ephemeris for the year 1901, and I look under the heading "Jupiter" on page 239, for the month of July. Opposite the 15th day of the month I find the right ascension to be 18 h. 27 m., neglecting the seconds. Now 27 minutes are so near to half an hour that, for our purposes, we may say Jupiter is in R.A. 18 h. 30 m. I set this down on a slip of paper, and then examine the declination column, where I find that on July 15 Jupiter is in south declination (the sign − meaning south, as before explained) 23° 17′ 52″, which is almost 23° 18′, and, for our purposes, we may call this 23° 20′, which is what I set down on my slip.

Chart No. 4.—From Right Ascension 12 Hours to 16 Hours; Declination 10° North to 30° South.

Next, I turn to Chart No. 5, in this chapter, where I find the meridian line of R.A. 18 h. running through the center of the chart. I know that Jupiter is to be looked for about 30 m. east, or to the left, of that line. At the bottom and top of the chart, every twenty minutes of R.A. is indicated, so that it is easy, with the eye, or with the aid of a ruler, to place the vertical line at some point of which Jupiter is to be found.

Chart No. 5.—From Right Ascension 16 Hours to 20 Hours; Declination 10° North to 30° South.

Then I consult my note of the declination of the planet. It is south 23° 20′. On the vertical borders of the chart I find the figures of the declination, and I observe that 0° Dec., which represents the equator of the

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