Robert Hatch

SUBTOPICS:

Astronomers and Astrology

OBJECTIVES:

The Students will:

1. identify the cardinal and intermediate directions
2. differentiate between geocentric and heliocentric models
3. appreciate how models help give a better understanding of things that cannot be fully observed
4. recognize that models change due to new or improved observations and technology
5. identify the major characteristics of the planets including their positions in the solar system
6. identify the relationship of astronomy and astrology
7. identify the origin of the names of the planets
8. identify technological improvements resulting in improved observation in astronomy

Background Information

The Greeks were certainly not the first to look up into the sky and notice the apparent motion of the sun, moon, and stars. They were, however, among the first to attempt to explain this motion and develop a model that would help them understand it. Greek thinkers did not all agree on one model, but developed the following two competing models.

The Geocentric Model

This model existed on the assumption that the earth was solid and permanent and was the steady, unmoving center of the cosmos. The stars were attached to a spherical shell which rotated around the motionless earth. The motion of the six visible planets was much harder to explain. These luminous “wandering stars” appeared to change their brightness and move against the backdrop of the other stars. The geocentric model explained each of these wandering stars as being attached to a sphere which revolved around the earth. Three of these, Mars, Jupiter and Saturn, were beyond the sphere of the sun. Mercury, Venus and of course the moon, were between the earth and the sphere of the sun.

This imaginary system of transparent or crystal spheres provided a model to describe the motion of the heavenly bodies. When observations conflicted with the model, changes were made by adding other spheres or epicycles to the existing spheres. The Greek astronomer Ptolemy (150 AD) eventually refined the eccentric model, accounting for all observable astronomical motion, to create a new model, which now bears his name–the Ptolemaic model.

Heliocentric Model

While some Greeks were developing the geocentric model, others proposed a different theory. Aristarchus (between 309-200 BC) proposed a new model which placed the sun at the center of the cosmos. The earth, the planets, and the stars were thought to rotate around the sun. The earth’s rotation on its axis and the tilt of its axis explained all the observed motions of the sky.

Nicholas Copernicus (1473-1543) furthered this view, although he is often credited with originating the sun-centered view and developing the Copernican model. Johannes Kepler (1571-1630) supported the Copernican model, and used data from the work of Tycho Brahe to develop further the Copernican model by explaining mathematically what is observed in the heavens.

Tychonic Model

Tycho Brahe (1546-1601), a Danish astronomer, accepted neither the Ptolemaic nor the Copernican models. He firmly believed the earth was at the center of the cosmos and stationary. However, some of his observations, which were the most precise of his time, could not be explained by using the Ptolemaic model. They could, however, be explained by using the Copernican model. But Brahe, refusing to bow to a moving earth, devised his own model which was observationally equivalent to that of Copernicus.

ACTIVITY #1:

Making Scientific Instruments: Directions for the Compass Rose

(can be used in later activities)
2 class periods

MATERIALS:

8 1/2 X 11 SHEET OF BLANK PAPER, COMPASS, PROTRACTOR, RULER, PENCIL

PROCEDURE:

1. First, following the directions below, make a transparency of the compass rose. This can be used to give the students a guide as they make their own.
2. Give the following verbal instructions. This can be a cooperative learning activity if you divide students into groups. Let the first student in each group complete the first set of directions and then pass the paper to the next student, who will complete the next set. When finished, each group will have one compass rose.

   Note: This design can also be used as stage decorations (stars) for the play performed at the end of the unit.

   1. Number the four corners of you paper: #1-upper right,#2-lower right, #3-lower left, #4-upper left. These will later be referred to as quadrants.
   2. Draw a horizontal line, parallel to the bottom of your paper 5 1/2 inches from the bottom, near the edges.
   3. Label the left end “W” and the right end “E”
   4. Make a perpendicular bisector, from top to bottom at midpoint.
   5. Place the point of the compass at point W and open the compass to extend past the midpoint of the line. Make a line (arc) above and below the line.
   6. Place the compass point on point E and, using the compass, make a line above and below the line which is close to the edge of the paper. The two lines at the top of the paper should intersect, and so should the two lines at the bottom. If they don’t, go back and make them longer until they do.
   7. Mark the point where the two lines on the top of your paper intersect and the point where the two lines on the bottom of you paper intersect and connect these two points with a line extending from the top of the paper to the bottom.
   8. Measure the angles created by these lines (should equal 90 degrees). Bisect the four angles and label the intersection of the two perpendicular lines, “X”.
   9. Measure 2 inches from X, on each of the four directions, and make a dot. Label the dot between X and N, “A” and label the dot between X and E, “B”. Label the dot between X and S, C. Label the dot between X and W, “D”.
   10. Open the compass 3 inches, place the point of the compass on A. Make a line quadrant 1 and 4.
   11. Open the compass 3 inches, place the point of the compass on B. Make a line in quadrant 1 and 2.
   12. Open the compass 3 inches, place the point of the compass on C. Make a line in quadrant 2 and 3.
   13. Open the compass 3 inches, place the point of the compass on C. Make a line in quadrant 3 and 4. Using a line, connect the intersection of the cross marks in quadrant 1 with the intersection of the crossmarks in 3. The line should pass through X.
   14. Using another line, connect the intersection of the cross marks in quadrant 2 with the intersection of the crossmarks in quadrant 4. The line should pass through X. Make a mark 1 1/2 inches above and below X on the diagonal lines. Label the dot in Quadrant 1, “F”. Label the dot in Quadrant 2, “G”. Label the dot in Quadrant 3, “H”. Label the dot in Quadrant 4, “I”.
   15. Measure the angle BXF (should equal 45 degrees). Connect N to F. Connect F to E. Connect E to G. Connect G to S. Connect S to H. Connect H to W. Connect W to I. Connect I to N.
   16. Label N, north. Label S, south, label W, west. Label E east.
   17. Make a mark 1 inch from F on line FN and FE. Label them F1 and F2.
   18. Make a mark 1 inch from G on line GE and GS. Label them G1 and G2.
   19. Make a mark 1 inch from H on line HS and HW. Label them H1 and H2.
   20. Make a mark 1 inch from I on line IN and IW. Label them I1 and I2.
   21. Connect F1 and F2 to the cross marks (intersecting arcs) in quadrant 1.
   22. Connect G1 and G2 to the crossmarks in quadrant 2.
   23. Connect H1 and H2 to the crossmarks in quadrant 3.
   24. Connect I1 and I2 to the crossmarks in quadrant 4
   25. Label the intermediate directions.
   26. Color it!

ACTIVITY #2:

More Instruments: Constructing a Sextant (Quadrant)

1 class period

MATERIALS:

5 INCH SQUARE OF POSTERBOARD, 1 COPY OF QUADRANT, 1 STRAW, SCISSORS, COMPASS, 1 PIN (for each student)

Background info for Activity

The earliest astronomers could rely only on naked-eye observation (with its obvious limitations) for astronomical data. Early observations were made primarily to determine time and seasons for planting and harvesting, and observations of the heavenly bodies were also used successfully in navigation. Thus the role of the sextant served primarily in early history to determine latitude.

Eventually, the sextant was also used to study the heavens for the purpose of understanding and explaining their mysteries. Tycho Brahe used the sextant (sixty degrees of arc) in his observatory of a quadrant (ninety degrees of arc) made of brass, fourteen feet in diameter. This allowed him to record the most precise astronomical observations of his time.

PROCEDURE:

1. Give each student a five inch square of cardboard or poster board.
2. Place the point of the compass at the corner of the cardboard and draw the largest possible arc. This arc should be 1/4 of a circle–a quadrant.
3. Cut along the arc.
4. Cut out a scaled quadrant resembling 1/2 a protractor.
5. Paste the scaled quadrant to the cardboard.
6. Attach a straw to the quadrant by placing a pin through the straw and the quadrant at the small circle in the corner.
7. When activity is completed, take the students outside to practice measuring angles from the horizon to the tops of trees or buildings. Do this until all students are comfortable with using the instrument.

ACTIVITY #3:

Making Observations to Determine the Movement of Constellations or Planets

(to be done by students after sundown)
2 class periods

PROCEDURE:

1. Select a location that is as free from outside light sources as possible, and can be returned to repeatedly.
2. Students must face one of the four cardinal directions: north, south, east, or west. This location should offer a sighting point to align with the star to be observed.
   
3. Sketch of the star’s position relative to the sighting point along with any other stars in close proximity. This could be helpful in locating the star on subsequent night observations.
4. Use the sextant produced earlier to determine the angle of the line of sight to the horizon. Be sure to hold the sextant horizontally.
   
5. Have students repeat the observations over the designated time and record any changes observed. Designate the number of days and times for observations.
   
   Note: The students can determine the direction they are facing by using their compass rose form Activity #1. Use the noon shadow as “N” or Polaris. Once the compass is correctly placed, the students can determine the direction they are observing. This should be practiced in class before students are to make the actual observations.
   YES NO
   °s above Shift to Shift to NO

   Date Time horizon Right Left Shift

   Sunset

   30 min.

   after

   Sunset

   1 hour

   after

   Sunset

   Hints: Give the students a week’s worth of time to perform the night observation recommended. Additional observations can be used as extra credit assignments.

6. After students have finished their observations, complete the data in the chart below.
   < Hori. < Hori. < Hori. Shift Shift No
    
   
   Students to star to star to star Left Right Shift
   
   Facing
   
   North
   
   Facing
   
   South
   
   Facing
   
   East
   
   Facing
   
   West
7. Have students make conclusions about the motion of the stars when facing each direction.
8. Ask students to draw conclusions on whether the stars move about a stationary earth or whether the earth moves.
9. Students should record time of moon rise and phase over a period of days.

ACTIVITY #4:

Our Place in Space

1-2 periods

PROCEDURE:

1. Present the 3 different models of the universe to the students (overhead, drawing on the board, ditto, etc. – see p. 10).
2. Have students compare and contrast the 3 models.
3. Have the students guess which model was proposed first, second and last. Discuss why they believe this and how early astronomers gather their information.

ACTIVITY #5:

Construct a Model of one of the Previously Mentioned Systems

2-3 class periods

MATERIALS:

TACKS, PINS, SCISSORS, STRING, WIRE, RULERS, GLUE, TAPE CONSTRUCTION PAPER AND MARKERS. STUDENTS PROVIDE OTHER WORKING MATERIAL.

PROCEDURE:

1. Design a scale, three-dimensional model illustrating the Ptolemaic Universe, the Tychonic Universe, or the Copernican Universe.
2. Divide the class into small groups.
3. On the first day, allow the students to plan, organize and begin working on the models.
4. On the second and third days, allow the students to use the period for completing models.
5. Display models in the media center or showcase. Award a prize for the one voted as “best” by the class (in terms of nearest, most colorful, most accurate, most detailed, etc.).

Note: This activity may seem chaotic, but allow the chaos, and give students as little direction as possible with respect to “how” to construct the models and what materials to use.

ACTIVITY #6:

Building a Galilean Telescope

30 minutes

MATERIALS:

2 CARDBOARD TUBES (ONE SLIGHTLY SMALLER IN DIAMETER), PAPER, PUTTY, 2 CONVEX LENSES (SHOULD HAVE DIFFERENT FOCAL LENGTHS)

PROCEDURE:

1. Give the following oral instructions to class:
   1. Place a convex lens at one end of each cardboard tube.
   2. Place the smaller tube inside the larger tube so that the lenses are at opposite ends.
   3. Focus on a object by looking in the smaller tube and slowly sliding the tubes back and forth.
2. Students should compare how several objects look when viewed with the unaided eye and with the telescope, students should and answer the following questions.
   1. What are some advantages of using a telescope?
   2. What are some technological advances that have been made since the telescope (satellites, space probes, space telescope)?

ACTIVITY #7:

Astrology: Roots in Astronomy

30 minutes

MATERIALS:

TWELVE PIECES OF CONSTRUCTION PAPER, OR SHEETS OF POSTER BOARD.

Background Information for Activity

The Babylonians practiced astrology in 2000 BC. Astrology remained linked to astronomy from the time of the Chaldeans to Ptolemy, and on through the Middle Ages. Involved were such scientists as Tycho Brahe and Johannes Kepler. The astronomical observations were the basis for complex mythology which became the foundation for astrological interpretations. This became increasingly popular in Europe, beginning in the 13th century. The twelve signs of the zodiac are determined by the twelve constellations. It was believed that these stars, the planets, and the sun ordained one’s destiny.

PROCEDURE:

1. Divide students into groups according to their zodiac sign (get dates and pictures from encyclopedia). The members of each group will research their constellation or zodiac sign. The groups will draw their constellations on posterboard or construction paper. Students can share their research with the rest of the class. They may also wish to discuss the rationality of basing predictions on the alignment of planets, constellations, as well as the sun.
2. Oversee the class in the following activities:
   1. Assign students bring to class a horoscope from a local newspaper.
   2. Have students share horoscopes, especially those of the same sign, and compare horoscopes of various newspapers.
   3. Discuss the possible reasons for early astronomers involvement in astrology.
   4. Have students discuss the requirements of scientific study. They should also present their results.
   5. Have students further discuss the rationale for predicting the future and for basing these predictions on constellations, planets and the sun.

ACTIVITY #8:

Derivation of the Planets’ Names in our Solar System

1 class period

MATERIALS:

STANDARD PICTURES OF THE GODS AND THEIR SYMBOLS, 9 DOWELS TO HOLD FLAGS OF EACH PLANET, CONSTRUCTION PAPER. FLAGS WILL BE USED IN THE PLAY OF ACTIVITY 9.

*Note: Teacher or students can draw the symbols.

PROCEDURE:

1. Present a short explanation to the class about mythology and the explanation for the natural phenomena centered around the actions of the gods and goddesses. The masses of people knew their names. However, few were literate. Therefore, it was necessary to develop a symbol that all would recognize. The symbol of the god usually related to its power.
2. Divide into nine groups–one for each planet–to research the particular planet and its symbol. Before making the flags, a class discussion will ensure the students understand mythology. The groups will make their respective flags of the planet’s symbol.
3. The nine planets are listed below. Since eight are named for Roman gods, information about them is listed concisely for whom each planet was named, the symbol it was given, and the use of that symbol today (if applicable).

   Planets:

   1. MERCURY was named after the messenger for the gods. Mercury wore a winged hat and sandals, similar to the FTD florist logo.
   2. VENUS was named for the goddess of love and beauty. Her symbol is the universal scientific symbol for a female.
   3. MARS is named for the god of war. His symbol, a skull and crossbones, is used as a warning for poison, and is also found on pirate flags. Another symbol is the universal scientific symbol for a male.
   4. JUPITER was named for the king of all gods and goddesses. His symbol is lightning, and is at times emitted from his hand.
   5. PLUTO is named for the god of the underground, or the dead. He is shown wearing long black robes and a hood. His figure is the symbol of death.
   6. NEPTUNE was named for the god of the sea. His symbol is a trident, the three pronged instrument often shown in drawings of evil.
   7. URANUS was named for the earliest Greek supreme god. He was the personification of the sky and heavens. He was eventually replaced by Cronus, and then Zeus. He wore a mantle dotted with stars and his hands always pointed to the sun and the moon.
   8. SATURN is named for the god of agriculture–sowing and harvests. He was represented as bearing a sickle.

Hint: If you are planning to enact the following play, the preceding information can be helpful in costuming the children appropriately.

ACTIVITY #9:

The Sun and Her Servants: A Play

approximately 1 week

PROCEDURE:

1. Students will perform the play depicting the solar system as it was viewed in the 1600’s and as it is seen now. You may use the play provided, or have students write a play of their own. If you choose to have students perform the play provided, the compass roses constructed in activity #1 can serve as a backdrop of stars. The flags made in activity #5 can be used as props, as can the scale models made in activity #6. The students can be costumed as suggested in activity #5.
2. Along with assigning the speaking parts, choose students to be in charge of costuming, props and perhaps scenery.
3. Students should research the planets they are assigned to perform.
4. You may wish to add high school students to help the elementary or middle school students put on the play.
5. Video tape the production and performances and use for other classes, especially lower grade levels, or perhaps even a PTA meeting.

Bibliography

Abell, George O. “Astrology.” The Science Teacher. 41 (1974): 9-13.

Crowe, Michael J. Theories of the World from Ptolemy to Copernicus.

Encyclopedia Americanan. “Astrology.” Vol. 12. 1990.

Gregory, Frederick. The Sun and Her Servants.

Shymansky, James A. Romance, Nancy and Larry D. Yore. Journeys in Science. New York: Macmillian, 1988. 178.

Stephens, David. Mythology. New York: Milliken, 1967.

Sutherland, Berry. Focus on Earth Science. Columbus: Merrill, 1984.

THE SUN & HER SERVANTS: A PLAY

The Characters:

Earth Mercury Jupiter Neptune
Moon Venus Saturn Pluto
Sun Mars Uranus

ACT I

The year is 1600

Enter Earth:

“Hello. My name is Earth. I have been around for a long, long time, and now , here in the year 1600, some people are saying that I, yes I, actually move! I mean, gosh. Did you ever hear anything so crazy! Do you feel like you’re riding on a moving Earth?

(Pause) No, I didn’t think so.”

“Everybody knows that it’s the planets and the stars that move, and I’m certainly not a planet. After all, the very word planet means ‘wanderer,’ and I don’t wander among stars.”

“However, some of my best friends are planets. There are only seven, you know. I’ll have them introduce themselves.”

Enter Moon:

“Hi. I’m the largest of the ancient wanders, uh, I mean planets. Do you know who I am? I’ll bet you don’t. I am the moon, and I go around the Earth in about one month. Watch, I’ll show you.”

(Moon walks around Earth, fairly close to her).

Enter Sun:

“She’s not the only planet. Most people call me one, too. I’m the brightest of the lot, though it takes me a whole year to go around the Earth. Do you know my name? I’m the sun.”

“The Moon and I have five sister planets, and all of us go around the Earth. I’ll introduce you to three of the others, the ones just beyond me, Mercury and Venus, and the one farthest from the Earth, Saturn.”

(Mercury, Venus and Saturn go out and take their positions)

“The other two, Mars and Jupiter, are in between Venus and Saturn.”

“Most people think, like I said, that we all go around the Earth, like this…

(Moon, Sun, Mercury and Saturn go around Earth)

“But a man from Denmark has been going around saying that only the moon and I go around the Earth, and the rest go around me! I like that idea. Watch how that would look….

(Moon and Sun circle Earth, and at the same time, Mercury and Venus go around Sun)

“Another man thinks that I am actually the center of all the planets–that I don’t move at all! I like that idea best! That snippity Earth would then be a planet like the others. It would serve her right. I do hope that history will show that I am queen of the solar system. But we’ll just have to wait and see.”

End of Act I

ACT II

The year is 1992

Sun (stepping forward):

“Hi! Remember me? Well, my hopes were all fulfilled. Today, in 1992, everybody agrees that I am the center of the solar system and that all the planets, including the Earth, revolve around me. I think it’s wonderful!”

“Scientists have found out a lot more about my subjects. I am going to let the planets tell you about themselves.

(Sun turns toward the planets)

“Subjects, don’t forget to show our guests how far each of you is from me by planting your flags on the playground at the proper distance.”

Enter Mercury, wearing a winter coat:

“Hello. I’m Mercury. You can only see me in the morning just before sunrise, or in the evening just after sunset. Brrrrrr! Am I cold! I’d invite you over for a visit, but the weather can be pretty unpleasant, you know. At midnight, I get down to 260 degrees below zero on the side of me away from the sun. That’s why I have to wear this heavy coat. But on my other side I’m blazing! (Mercury takes off her coat) 660 degrees! Can you imagine it? Talk about running hot and cold! I guess it’s because I’m the planet closest to the sun, but if you ask me, it’s ridiculous!”

(Mercury plants her flag 4 steps from the sun)

Enter Venus:

“My name is Venus. You know me–the goddess of love? I’m very bright; in fact, I’m the brightest object in the sky after the sun and the moon. Like Mercury, you can see me only in the morning and evening. Because of my brightness, I’m called the morning and evening star. Also like Mercury, I can be pretty hot–up to 900 degrees on my surface!”

“It pains me to say this, but I, a goddess, have no moons. A frightful circumstance! Well, at least my atmosphere is different from Earth’s. It’s 97% carbon dioxide–that makes it 90 times heavier than Earth’s. Maybe you’d better

not come over for a visit just yet. Of course, if you’re a planet I guess you’d love it here. But then my day is longer than my year–odd, huh. Well, no one ever said love was reasonable.”

(Venus plants her flag 7 steps from the sun.)

Enter Earth, looking bewildered:

“I just don’t know what happened. Here I was, the center of the universe. Next thing I know I’m the third planet out from the sun. Why me? I had it so good.”

(muttering) “I just don’t know what happened.”

(Earth plants her flag 10 steps from the sun.)

Enter Mars (marching):

“Hut, 2, 3, 4. Hut 2, 3, 4. I guess you don’t have to be told who the God of War is, right? You know I’m Mars, so I won’t even mention my name. I’m actually the last one of the group of us who is close to the sun. The rest of the planets can get a long way out there, as you’ll see.”

“One of the most unusual things about me, besides the fact that I look red in the sky, is that Deimos, one of my two moons, goes around me in one direction, while Phobos, the other one, insists on going around me in the opposite direction. I do wish they could have agreed. In the whole solar

system, Phobos is the only moon that rises in the west and sets in the east. Independent cus, that Phobos. Oh well, I must be off. Hut, 2, 3, 4. Hut, 2, 3, 4.

(Mars plants her flag 15 steps from the sun)

Enter Jupiter (muttering to herself):

“Now where did I put the lightning bolt? (Notices the audience) Oh, hello there. Excuse me, but I’ve misplaced some of my lightning bolts. Jupiter’s the name–Zeus to the Greeks. I’m the king of the Gods. What’s that? Why? Well, probably because I’m the biggest. I’m more than 1000 times bigger than the Earth, you know. And I have 12 moons–that’s the big one-two, twelve. And, it takes me twelve years to go around the sun. And, I have twelve giant red spots–well, OK–one giant red spot. But at least I’ve baffled everybody

about it. No one knows for sure what it really is. It’s necessary for us Kings to be a little mysterious, you know. Keeps everybody on their toes.”

(Jupiter turns away from the audience and mutters to himself)

“Now, what did I do with those lightning bolts?”

(Jupiter plants his flag 52 steps from the sun)

Enter Saturn:

“I may not be quite as big as she is (points to Jupiter), but I’ve got something she doesn’t–my 4 lovely rings! Yes, I know I’m not the only planet with rings, but I definitely have the most famous ones. I wear them well, if I do say so myself. You probably already know that they’re made of small particles coated with ice.”

“In the old days, I was the last planet–the one farthest from the sun. It takes me 29 Earth years to go all the way around the sun.

(Saturn assumes a sad look, and sighs)

“But, alas, now there are three new planets in the solar system that weren’t known about back in 1600, so I’m not the farthest any more.

Saturn brightens up, and says cheerfully:

“But, I’ve still got my rings! Yes sir! I’ve still got my rings. Don’t they look simply divine?”

(Saturn plants her flag 95 steps from the sun)

Enter Uranus and Neptune, and say, in unison:

“We’re the twin planets, Uranus and Neptune.”

Neptune:

(Pointing to Uranus)

“When she was first noticed, she was mistaken for a comet.”

Uranus:

(Pointing to Neptune)

“When she was discovered she caused a sensation. See, I was misbehaving so badly in my orbit, not going where I was supposed to, that people said: ‘somebody else must be up there making Uranus misbehave like that.’ Sure enough, when they looked closer, they found ol’ Neptune here.

Neptune:

“We might be twins, but I’ve got farther to go. It takes me 165 Earth years to go around the sun–imagine that! Some people say that I was once a moon of Uranus, but (Neptune puffs out her chest) now I have 2 moons of my own.”

Uranus:

“I thought you looked familiar! Well, I’ve still got five moons left who didn’t go running off on their own. Incidentally, (turning to Neptune) you’d better get going to your position or we’ll have to wait all day for you, you’re so far away from the sun.”

(Uranus plants her flag 182 steps from the sun, Neptune 300 steps.)

Enter Pluto:

“Is it my turn? Finally! I’m always last. They think they’re a long way out. Hummmpf. They don’t know the meaning of the word far. They should visit me sometime–if they could take the 400 degrees below zero, that is. I’m so far away from the sun that my trip around is just now bringing me back to where I was when the Pilgrims were discovering America. I have to get going to my position now. But, before I go, would you all please do me a small favor? Would you all try to remember that, in spite of my name, I was not named after Mickey Mouse’s dog? Thanks a lot. Now, watch how far away from the sun I am.”

(Pluto plants her flag 395 steps from the sun)

Sun:

“As Queen of the Solar System, I want to thank you all for your visit with us. We’re glad you go to meet us, and we hope you enjoyed learning a little bit about us. ”

“Thank you very much.”

All the actresses step forward next to the Queen and bow together.

END OF ACT II

Attachment A

Nicholaus Copernicus

The medieval view of the universe was a combination of church teachings and the theories of Aristotle and Ptolemy, which viewed the earth as the center of the cosmos. When, in the second century AD, Ptolemy pictured the cosmos with the earth at the center, medieval thinkers accepted it and continued to believe that around the earth revolved seven “planets”– the moon, the sun, Mercury, Venus, Mars, Jupiter and Saturn. Medieval astronomers believed they could see these heavenly bodies moving across the sky. This earth centered view of the universe was called the geocentric theory, and it reflected the Christian view that God had designed the universe especially for human beings.

In the 1500’s, Nicholas Copernicus came across ancient writings which argued that the sun was the center of the cosmos. This was the Heliocentric Theory. It’s name was derived from the Greek word “helios,” meaning sun. The ancient theory interested and excited Copernicus, and he began a long period of study and observation. Convinced that all known facts of astronomy were best explained by the heliocentric theory, he published his conclusions in On the Revolutions of the Heavenly Spheres (1543).

The book caused little excitement, largely because few people believed in the heliocentric theory. It seemed to contradict the evidence of the senses, as virtually anyone could “see” that the sun and planets moved around the earth and could “feel” that the earth was solid and not moving.

Copernicus could not test and prove the heliocentric theory with the instruments or the mathematics available. Proof had to wait for the work of two later scientists, Kepler and Galileo.

Tycho Brahe

Tycho Brahe, 1546-1601, was born in Denmark along with a twin who died at birth. He was supposedly always trying to do the work of two.

Like Renaissance artists, scientists of this time often depended on royal or wealthy patrons. Brahe worked first for the Danish king. With royal support, he built one of the earliest modern observatories, Uraniborg, which means “fortress of the skies.” Brahe agreed with part of the Copernican theory–that planets move around the sun–but still believed the sun circled the earth once a year. About 1600 Brahe began to work at the court of the Holy Roman Emperor in Prague. Johannes Kepler moved there to assist the older astronomer and published Brahe’s work after the Danish scientist’s death in 1601.

Unlike Kepler’s belief, Brahe’s belief in astrology was not derived from mysticism, which was completely alien to his domineering nature, but from stark superstition.

Brahe’s fame as the leading astronomer of his time, was the new star of 1572. In Tycho’s life, all the decisive landmarks were sky marks: the eclipse of the sun when he was fourteen (which brought him to astronomy), the conjunction of Jupiter and Saturn when he was seventeen (which made him realize its insufficiencies), the new star when he was twenty-six, and the comet of 1577, five years later. Of all these, the new star, called Super Nova, was the most important. The Tychonian System was basically built on the idea that the earth was reinstated as the center of the world, the five planets were circling around the sun, and, with the sun, all revolved around the earth. This was obviously a revival of the intermediary system between those of Herakleides and Aristarchus of Samos. Tycho’s system, therefore, was a compromise between the Copernican ptolamaic and an alternative and viable world.

Brahe invited Kepler to work with him because he needed Kepler’s brilliant mind. The association between Kepler and Brahe lasted eighteen months, until Brahe’s death.

Tycho Brahe died a rather unusual death, simply because he had over indulged in food and drink. Brahe was buried with great pomp in Prague. His coffin was carried by twelve imperial gentlemen-at-arms, preceded by his coat of arms, his golden spurs, and his favorite horse.

Two days later, Kepler was appointed to be Brahe’s successor, the Post of the Imperial Mathematician.