Science 9 Chapter 10 notes.ppt

Page 1: Overview

• TITLE: SCIENCE 9 CHAPTER 10 SECTION 1 Observing the Stars (pp. 352-365)

Page 2: Celestial Bodies

• Celestial Body: A natural object in space (e.g., Sun, Moon, planet, star).

• Star: A celestial body of hot gases with a core nuclear furnace generating thermal energy.

• Planet: A celestial body that:

  • Orbits one or more stars.

  • Is large enough for its gravity to hold it in a spherical shape.

  • Is the sole body in its orbital path.

Page 3: Constellations

• Constellation: Pattern of stars in the night sky resembling familiar objects.

  • Often named after characters from Greek and Roman mythology.

• Used by amateur astronomers to locate other celestial objects.

• 88 constellations officially recognized by the International Astronomical Union, e.g., Leo, Cassiopeia, Orion.

• Stars in a constellation may be of varying distances from Earth despite appearing close together.

Page 4: Asterisms

• Asterism: A star pattern that is not an official constellation.

  • Can consist of stars from within a constellation or different constellations.

  • Example: The Big Dipper.

• Pointer Stars: The two stars at the end of the Big Dipper (point toward the North Star, Polaris).

• Polaris: Not the brightest star despite common belief; only as bright as stars in the Big Dipper.

• Canadians cannot see all 88 constellations, with approximately 20 not visible from the northern horizon.

Page 5: Magnitude of Stars

• Magnitude: Apparent brightness of a star as seen from Earth.

• Developed by Hipparchus in 134 B.C.E.:

  • Brightest stars = Magnitude 1.

  • Next-bests = Magnitude 2, etc., down to Magnitude 6 (faintest visible stars).

• Modern scale includes negative numbers for brighter objects (e.g., planets can reach –4).

Page 6: Angular Dimensions

• Angles between stars can be measured in degrees for precise communication of star positions.

• Circle has 360°, with 90° from horizon to zenith.

• Full Moon subtends 0.5°.

• Estimation using hand measurements (held at arm's length):

  • Fingernail = 1°

  • Three fingers = 5°

  • Fist = 10°

  • Outspread two fingers = 15°

  • Outspread thumb and little finger = 25°.

Page 7: Movement of Stars

• Stars appear to move from east to west due to Earth's rotation.

• Stars rise in the east and set in the west;

  • North-viewers see them rotate around Polaris (the North Star).

  • Polaris is found at the end of Ursa Minor (Little Dipper).

Page 8: Circumpolar Constellations

• Circumpolar Constellations: Never set below the horizon.

  • Include Ursa Major, Ursa Minor, Cassiopeia, etc.

Page 9: Motion of the Sun, Moon, and Planets

• Ecliptic: Path of the Sun through the sky from Earth's perspective.

  • Zodiacal Constellations: 12 star groups for zodiac signs (e.g., Aries, Taurus).

Page 10: Planetary Motion

• Planets revolve at different rates around the Sun along the ecliptic.

• Inner Planets (Mercury and Venus):

  • Move faster; seen near the Sun.

  • Visible shortly after sunset or before sunrise.

• Outer Planets: Visible throughout night depending on their position relative to Earth.

Page 11: Seasonal Constellations

• Earth’s annual orbit alters visible constellations each season.

• Some constellations are visible year-round; others only in specific seasons.

Page 12: Fall Constellations

• Fall: Constellation Pegasus dominates, characterized by a large square shape.

  • Ecliptic Constellations: Aries, Pisces, Aquarius, Capricornus (dim).

Page 13: Winter Constellations

• Winter: Orion, known for bright stars, is central.

  • Surrounding constellations: Gemini, Canis Major, Taurus, Auriga.

  • Sirius: Brightest star in Canis Major.

Page 14: Spring Constellations

• Spring: Leo the Lion stands out, with Ursa Major overhead.

Page 15: Summer Constellations

• Summer: Cygnus, Lyra, and Aquila are prominent.

  • Bright stars (Deneb, Vega, Altair) form the Summer Triangle.

Page 16: Chapter Transition

• TITLE: SCIENCE 9 CHAPTER 10 SECTION 2 Early Models of the Universe (pp. 366-375)

Page 17: Ancient Observatories

• Early societies used celestial patterns for navigation and seasonal awareness.

• Notable ancient structures for observing celestial movements include:

  • Chichén Itzá (Mexico), Stonehenge (England), Pyramids of Giza (Egypt), Bighorn Medicine Wheel (Wyoming).

Page 18: Aristotle

• Aristotle (383–322 B.C.E): Greek philosopher who theorized a geocentric universe.

  • Observed lunar eclipses and concluded Earth is spherical based on evidence of different constellations seen at different latitudes.

Page 19: Aristarchus of Samos

• Heliocentric: Theory proposing the Sun is the center of the universe.

• First to measure the distance to the Sun and claim planets revolve around it.

Page 20: Eratosthenes of Cyene

• Eratosthenes (276–194 B.C.E): Mathematician who accurately measured Earth’s diameter using simple methods.

Page 21: Eratosthenes' Measurement Method

• Method involved measuring shadows cast by two sticks at different locations to calculate Earth’s circumference, achieving an impressive accuracy of 41,143 km.

Page 22: Ptolemy

• Ptolemy (83–168 C.E): Developed a solar system model with earth-centered orbits and retrograde motion.

  • Observed Mars and introduced the concept of epicycles to explain its movement.

• Developed the Astrolabe for celestial navigation.

Page 23: Copernicus

• Nicolaus Copernicus: Introduced a simpler heliocentric model before the telescope.

  • Proposed daily rotation of Earth and yearly revolution around the Sun.

Page 24: Galileo

• Galileo: Utilized a telescope for astronomical observations.

  • Discovered moons orbiting Jupiter, provided evidence for the heliocentric model through observations of Venus’s phases.

Page 25: Chapter Transition

• TITLE: SCIENCE 9 CHAPTER 10 SECTION 3 Standing on the Shoulders of Giants (pp. 376-385)

Page 26: Johannes Kepler and Tycho Brahe

• Orbit: The path of a celestial body around another body.

  • Worked with Brahe to formulate laws of planetary motion and the concept of celestial orbits as elliptical shapes.

Page 27: Kepler’s Laws of Planetary Motion

• Kepler’s Three Laws:

  1. All planets move in ellipses with the Sun at one focus.

  2. Planets cover equal areas in equal times, changing speed based on proximity to the Sun.

  3. The time taken for a planet to orbit the Sun relates directly to its distance from the Sun.

Page 28: Sir Isaac Newton

• Newton (1643–1727): Pioneered laws of motion and universal gravitation extending beyond Earth's surface to all celestial bodies.

Page 29: Scale of the Solar System

• Outer Planets: Neptune discovered in 1846 based on deviations in Uranus's orbit.

  • Distance between planets is vast, with many regions in the solar system void of matter.

Page 30: Structure of Solar System

• Inner Planets: Mercury, Venus, Earth, Mars; Rocky, solid cores.

• Outer Planets (Jovian): Jupiter, Saturn, Uranus, Neptune; Gaseous atmospheres, lacking solid surfaces.

Page 31: Summary of Solar System Planets

• Listing of planets: Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.