Universe Cycle - Universe (6)

  • Comparing the night sky with zodiac signs.
  • Discovering the difference between the zodiac signs and astronomy.
  • astronomy
  • zodiac

Students determine if "zodiac" is scientific.

Supernova rings


When students begin the study of astronomy, a clear distinction must be made between astronomy and astrology. Astronomy deals with the study of the location, motion, and nature of objects in space. Astrology is the interpretation of the influence of the heavenly bodies on human affairs. Astrology is not a science; its results are not repeatable nor consistent.

In lab, the students will try and locate different objects in the Universe by learning to read celestial globes. These are projections of the sky onto a spherical surface, which is called the celestial sphere. Within the celestial sphere, the north and south celestial poles are points in the sky that seem fixed. The remaining stars and celestial objects appear to rotate around them. In the Northern Hemisphere, the celestial pole is marked by Polaris, the "North Star". To illustrate the celestial poles, you can use an open umbrella. The pole of the umbrella represents the celestial pole; the top of it would be the North Star. As you rotate the umbrella, it shows how the Northern Hemisphere constellations seem to move in the night sky.

A constellation is an apparent grouping of stars and galaxies, as viewed from Earth. They are often named for a mythical figure, animal or inanimate object. There are 88 sectors of the Universe named for constellations. Astronomers use these to locate sections of the sky. Well-known ones include Orion, Hercules, and Pegasus.

About 8 degrees north and south of the ecliptic (a band across the sky between the highest (summer) and lowest (winter) point of the Sunís apparent path) there are 12 constellations called the zodiac. Because of the Earth's motion around the Sun, the Sun appears to pass in front of each zodiacal constellation once per year, always in the same order. For example, the Sun is at Pisces at the beginning of spring and then moves through, Aries, Taurus, and so on.

The zodiac constellations serve as reference points to astronomers when investigating the Universe. However to astrologers, the zodiac constellations, as well as the motions of the planets, were signs believed to influence the behavior and lives of people (i.e.,  finances, relationships, moods, friendships). There is no scientific basis for these interpretations.

  1. Discuss with students the constellations in the sky and how they are named for mythical figures.  Emphasize that the Zodiac constellations were thought to be special because they were within the ecliptic.  Use the song to emphasize the difference and to locate the different constellations.  

  2. As a class, see if you can figure out the zodiac signs by using the birthdays of the students. Most of them probably know their astrological signs. Write the information on the board, as shown in the table below.

CAPRICORN - December 22 - January 19
AQUARIUS - January 20 - February 18
PISCES - February 19 - March 20
ARIES - March 21 - April 19
TAURUS - April 20 - May 20
GEMINI - May 21 - June 20
CANCER - June 21-July 22
LEO - July 23 - August 22
VIRGO - August 23 - September 22
LIBRA - September 23 - October 22
SCORPIO - October 23 - November 21
SAGITTARIUS - November 22 - December 21

  1. Instruct students to examine the Celestial Globes and try to determine which constellations are visible during each month of the year. Have them determine if the zodiac signs really correspond to what is showing in the night sky during those months (they do, but poorly at best). Remember, to read the Celestial Globe, you first find the month, which is written on the celestial equator. Next, find the longitude at which you live, and look at the "area" of the sky around that point. This tells you what celestial objects are visible at that time. Make sure the students read the globe from the correct hemisphere.
  2. You may want  students to make a sky cap.  Cut out the sky cap and assemble them. This is part of the exercise will help the students focus on one specific month, so they see that other "zodiac signs" are in the sky at the same time.  This cap is for the November sky (40 degrees north).

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