Physical Science Quarter 2, Astronomy, Past Notes PDF

GOOD MORNING Physical Science - Quarter 2  ASTRONOMY is the study of everything in the universe beyond Earth's atmosphere. That includes objects we can see with our naked eyes, like the Sun , the Moon , the planets, and the stars. It also includes obje...

GOOD MORNING Physical Science - Quarter 2  ASTRONOMY is the study of everything in the universe beyond Earth's atmosphere. That includes objects we can see with our naked eyes, like the Sun , the Moon , the planets, and the stars. It also includes objects we can only see with telescopes or other instruments, like faraway galaxies and tiny particles.- Google.com Astronomy is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, and comets. Wikipedia  WEEK 1 - OBJECTIVES ⮚ 1. Explain how the Greeks knew that the Earth is spherical. S11/12PS-IVa-38 ⮚ 2. Cite examples of astronomical phenomena known to astronomers before the advent of telescopes. S11/12PS-IVa-41 ⮚ Explain how Brahe’s innovations and extensive collection of data in observational astronomy paved the way for Kepler’s discovery of his laws of planetary motion. S11/12PS-IVb-44  LESSON 1 How the Greeks knew that the Earth is spherical?  ANAXAGORAS ❑ He attempted to give a scientific account of eclipses, meteors, rainbows, and the Sun, which he described as a mass of blazing metal. ❑ Anaxagoras taught that the sun was a hot rock, and that the moon shone from the reflected light of the sun. He also understands that eclipses are caused when the moon passed through the shadow of the earth (a lunar eclipse) or when the moon gets in between the sun and the moon (a solar eclipse.) ARISTOTLE ❑ Student of Plato ❑ Tutor of Alexander the Great ❑ Provided observational arguments including the positions of the North star, shape of the moon and the sun, and disappearance of the ship when sailing in the horizon.  ARISTOTLE’S OBSERVATIONS ⮚ In an eclipse of the Moon, the Earth’s shadow is always circular; a flat disc would cast an oval shadow. ⮚ The North star is believed to be in fixed position, but if you travelled on places near the equator it is noticed that it is closer to the horizon. ⮚ If the Moon and the Sun were both spherical then the earth must be spherical. ⮚ If the Earth was flat, then a ship travelling away from the observer should become smaller and smaller until it disappeared but instead they observed that the ship became smaller and then its hull disappeared first before the sail as if it was being enveloped by the water until it completely disappears.  ERASTOTHENES ❑ He is best known for being the first person to calculate the circumference of the Earth , ❑ He was also the first to calculate the tilt of the Earth's axis, which also proved to have remarkable accuracy.  HISTORICAL MODELS OF UNIVERSE They believed that earth is the center of the universe (geocentrism) while the alternative viewpoint to the geocentric system was that the Sun is the center of the universe (heliocentrism). Among the first Greek philosophers to suggest a geocentric system were Eudoxus, Aristotle and Ptolemy. On the other hand, the proponents of heliocentric system were Aristarchus and Copernicus (Bayo-ang 2016).  EUDOXUS UNIVERSE (408 BC) Eudoxus’ model placed the spherical Earth at the center of the universe. The Sun and the planets were then placed in giant transparent spheres that orbit the Earth. The Sun’s sphere orbits the Earth once every 24 hours, and the stars are attached to a larger sphere beyond this. A model of the universe that has the Earth at the center is known as a geocentric universe (Figure 3.2)  ARISTOTELIAN UNIVERSE (384- 322 BC) Aristotle believed that space is fundamentally different from the Earth because he thought that objects in space are unchanging and move in perfect circles, which he considered to be the perfect shape. In contrast to this, the Earth is imperfect and constantly changing  PTOLEMAIC UNIVERSE Ptolemy is a great proponent of the geocentric model. He saw that there were problems with Aristotle’s simplistic idea of a geocentric model. Ptolemy employed an old idea of epicycles to explain the discrepancies in the evidence for geocentrism. Although he was able to make more accurate predictions than previous astronomers, his model still failed to be completely accurate. Ptolemy had introduced the concept of ARISTARCHUS UNIVERSE (310- 230 BC)  COPERNICAN UNIVERSE ❑ Nicholas Copernicus, a Polish astronomer, was the first great astronomer in a long time. His model states that “Earth was just another planet. Earth rotates on its axis, the moon orbits the Earth” ❑ Copernicus believed that the planets only travel in perfect circles, and so his heliocentric model needed a similar amount of epicycles in order to explain their observed motions.  LESSON 2 Astronomical Phenomena before the Advent of Telescope  ASTRONOMICAL PHENOMENA KNOWN TO ASTRONOMERS BEFORE THE ADVENT OF TELESCOPES. Even before the advent of the telescopes, ancient astronomers were able to observe the: ❑ rising and setting of the Sun in the east and the west, respectively, ❑ point where the Sun rises and sets in the horizon varies in a year, ❑ phases of the moon, ❑ lunar eclipse, ❑ solar eclipse, ❑ daily and annual motion of the stars, and ❑ planets Mercury, Venus, Mars, Jupiter, and Saturn.  LESSON 3 Brahe’s Innovations and Kepler’s discovery of Planetary Motion  Tycho Brahe (1546-1601) was born of Danish nobility three years after the death of Copernicus Brahe became interested in astronomy while viewing a solar eclipse that had been predicted by astronomers He influenced King Frederick II to build an observatory near Copenhagen The telescope had not yet been invented Supernova explosion of 11 Nov 1572 — named “Nova Stella”, now SN 1572 (b) Comet in 1577 (c) Better and more reliable astronomical data (precise measurement of the locations and orbits of celestial bodies) ⮚ Inform them that Kepler was hired as sort of “research assistant” by Brahe primarily to prove that Brahe’s model (geoheliocentric model) of the Universe is consistent with the available data. ⮚ Kepler needed Brahe’s data to do mathematical analysis while Brahe needs Kepler to make mathematical calculations to prove that the model satisfies the observed data. ⮚ Brahe died before his model is proven. Kepler inherited vast data set that will prove crucial for developing his Three Laws of Planetary Motion later.  JOHANNES KEPLER was a German astronomer, mathematician, and astrologer (1571-1630) Kepler had a good mathematical mind and a strong faith in the accuracy of Brahe’s work after about 20 years or so working with the data he got from Brahe, the Three Laws of Planetary Motion were published in two different years: (1) Law of Orbit (1609) (2) Law of Equal Area (1609) (3) Law of Period (1619)  1. LAW OF ELLIPSE: The orbit of each planet about the Sun is an ellipse with the Sun at one of the foci of the ellipse. 2. LAW OF EQUAL AREAS: The line joining the Sun and the planet (called the “radius vector”) sweeps over equal areas in equal times as the planet travels around the orbit. 3. LAW OF PERIOD The square of the period of revolution (time for one complete orbit) of a planet around the Sun is proportional to the cube of the average distance of the planet from the Sun. (P2=a3)  Therefore, the solar distances of the planets can be calculated when their periods of revolution are known  PERFORMANCE OUTPUT NO 1. PROVING THE EARTH IS ROUND Materials: paper plate (or used folder-cut into circle) popsicle sticks (or ordinary sticks) scissors scotch tape (or glue) flashlight (or flashlight from cellular phone ) Procedures: 1. Near the edge of the paper plate, mark two places directly across from each other. 2. Make a small hole in each mark and put the popsicle stick in each hole. 3. Hold the paper plate vertically in front of the flashlight then observe the shadow cast by the popsicle stick. 4. Bend the paper plate slightly in front of the flashlight then observe again the shadows cast by the popsicle stick. 5. Guide Questions: 6. 1. What can you say about the shadow cast by the popsicle stick when the paper plate is placed vertically in front of the flashlight? ____________________________________________________________________________________ 7. 2. When you bend the paper plate slightly near the flashlight, do the two sticks still cast shadows of the same length? Why? _______________________________________________  PERFORMANCE OUTPUT NO. 1 ACTIVITY: DRAWING ELLIPSES WITH STRING Materials: string thick cardboard (or any similar material) paper sharp pencils thumbtacks (or any similar pins) Procedures: 1. Place the sheet of paper on the cardboard and secure the paper with two thumbtacks. 2. Tie the string into a loop and hook it around the thumbtacks. 3. Pull the loop tight with the point of a sharp pencil. 4. Keep the loop tight, then move the pencil around to draw the ellipse. Write your observations. 5. Try to do it again, but this time try to change the total length of the string used and vary the distance between the pins. 6. Guide Questions: 7. 1. How can you make the ellipse rounder? Flatter? 8. 2. What did you observe if the two thumbtacks are right next to one another?