Physical Science

1. Physical Science Solar System Slides subject to change

2. Psalm 19 1 The heavens declare the glory of God; the skies proclaim the work of his hands. 2 Day after day they pour forth speech; night after night they display knowledge.

3. Geocentric Model • Ptolemyca 140 A.D. • Egyptian astronomer. • Geocentric system (Earth-centered). • Stars and planets are embedded in rotating spheres, with Earth at the center. • Spheres made of an aetherial transparent fifth element (quintessence). • Like jewels set in orbs. Medieval chemistry – four elements earth, air, fire, and water.

4. Geocentric Conclusions • Earth surrounded by “rotating” spheres. • Outer sphere beyond the stars is unmoving—where God dwells.

5. Some Biblical Arguments • Psalm 93:1 “... The world is firmly established; it cannot be moved.” • Psalm 104:5 “He set the earth on its foundations; it can never be moved. • Why don’t these work?

6. Heliocentric Model • Nicolaus Copernicus, Polish astronomer. • Proposes heliocentric system, • Orbits of planets are perfect circles, with the Sun at the center. • Fears criticism, and sees first printed edition of his work as he dies in 1543.

7. Heliocentric − “Sun” in the Center

8. Scientific Method • Observe some aspect of the universe. • Invent a tentative description, called a hypothesis, consistent with what you have observed. • Use the hypothesis to make predictions. • Test those predictions and modify the hypothesis in the light of your results. • Repeat steps 3 and 4 until there are no discrepancies between theory and experiment and/or observation.

9. Need Accurate Data • Tycho Brahe1546 – 1601 • Significant work about1600 A.D. • Danish nobleman. • Most accurate astronomical measurements of his time. • No telescope. • Unusual geocentric model, “the Earth is just too sluggish to be continually in motion.”

11. Need Accurate Data • Johannes Kepler1571 – 1630 • Significant work 1605 A.D. • German mathematician, assists Tycho Brahe. • Believes heliocentric solar system, and tries to convince Tycho. • Finds the orbits are mathematical ellipses. • Three laws of planetary motion.

12. Kepler’s Orbit Model

13. Other Figures • Galileo Galilei 1564 – 1642 • Significant work 1632 A.D. • Italian physicist. • Observed sky with telescope. • Moon has craters, Jupiter has moons, Venus has phases. • Champions Copernicus. • He’s in Big trouble with Pope.

14. Other Figures • Isaac Newton1642 – 1727 • Significant work 1667 A.D. • English mathematician, physicist. • Degree from Cambridge in 1665, university closes due to Plague, he goes home. • Proposes celestial and terrestrial physics are related (apple incident). • Law of gravity, attraction between masses.

15. Kepler’ Three Laws • All planets move in elliptical orbits around the Sun, with the Sun at one focus of the ellipse. • An imaginary line joining a planet to the Sun sweeps out equal areas in equal time. Animation: Beige areas have equal areas. http://www.astrobio.nau.edu/~koerner/ast180/lectures/pic/cdrom/animations/movie-02-04.swf • (period)2 = k (semi-major axis)3

16. Example of Kepler’s 3rd Law • Let T = period, and R = semi-major axis • = k • For Mars, find orbital period T : • k = = • T2 = (1)2 x = 3.51 • T = sqrt (3.51) =1.87 “Earth” years Earth Mars

17. Rochester, NY Lima, Peru Measuring Distances Using Parallax Mars Parallax from different locations Trigonometry Images from Michael Richmond, RIT

18. Pluto’s too tiny. Nine Planets • Mercury • Venus • Earth • Mars • Jupiter • Saturn • Uranus • Neptune • Pluto

19. Mercury Venus Earth Mars Inner Planets Size to Scale

21. #3 Earth • Diameter: 7,900 mi or 12,740 km. • Mass: 6.0x1024 kg • Density: 5.52 g/cm3. • Acceleration due to gravity: 1 g or 9.8 m/s2 or 32 ft/s2. • Temp: -88°C→ 58°C • Orbital radius (mean) 93x106 miles, 150x106 km, or 1 AU • Earth Year: 365.25 days • Earth Day: 24 hours

22. Moon • Diameter: 0.27 Earths (~1/4 Earth diameter) • Mass: 1.2% Earth • Density: 3.35 g/cm3 • Gravity: 0.16 g (~1/6 Earth gravity) • Orbital radius (mean) 384,000 km • Lunar Earth Orbit: 27.3 days • Lunar Day: 27.3 days (same side always faces Earth)

23. Earth’s Atmosphere

24. Precession: 26,000 y period. Axial Tilt 23.5° .

25. Ecliptic • Earth reaches its closest distance to Sun in January. • The Earth travels to its farthest point from the Sun in July.

26. Other Planets

27. Relative Sizes • Compare the Sun to the size of a 26-inch diameter exercise ball: • Earth ¼ inch in diameter (pea-size), about 230 feet away (in the student parking lot). • Pluto about 2 miles away (at Irwindale Costco). see demo

28. #1 Mercury Closest to Sun, hot • Diameter: 0.383 Earths • Mass: 8.5% Earth • Density: 5.43 g/cm3 • Gravity: 0.38 g • Equator Temp: –170 → 430 °C (hot enough to melt lead) • Orbital radius (mean) 0.387 AU • Mercurian Year: 88 days • Mercurian Day: 58 days

29. #2 Venus Enshrouded in clouds • Diameter: 0.950 Earths • Mass: 0.815 Earth • Density: 5.20 g/cm3 • Gravity: 0.90 g • Mean Temp: 460 °C (also hot enough to melt lead), evenly distributed. • Orbital radius (mean) 0.723 AU • Venusian Year: 225 days • Venusian Day: 243 days (slow) Atmosphere: Carbon dioxide, some sulfuric acid

30. Moon Venus 9/9/13

31. #4 Mars Red planet • Diameter: 0.533 Earths • Mass: 0.107 Earth • Density: 3.93 g/cm3 • Gravity: 0.38 g • Temp: –107 °C→ –17 °C CO2 freezes into dry ice. • Orbital radius (mean) 1.52 AU • Martian Year: 687 days • Martian Day: 24.6 hours Atmosphere: 95% Carbon dioxide, 2.7% N2 Surface, Mars Viking

33. Mars Exploration • Mars Science Laboratory • Nicknamed “Curiosity” • Launched November 26, 2011 • Successfully landed in Gale Crater on August 6, 2012. • Mars Springtime in 2020

34. Outer “Jovian” Planets

35. #5 Jupiter Gas giant • Diameter: 10.8 Earths • Mass: 318 Earths • Density: 1.33 g/cm3 • Gravity: 2.53 g • Temp: Cloud top –145 °C, hot interior • Orbital radius (mean) 5.20 AU • Jovian Year: 11.9 Earth Years • Jovian Day: 9.9 hours Mostly hydrogen and helium

36. Galilean Moons Io, Europa, Ganymede and Callisto.

37. Jupiter, Io, and Shadow, Cassini

38. #6 Saturn Stunning rings • Diameter: 9.0 Earths • Mass: 95 Earths • Density: 0.69 g/cm3(less than water) • Gravity: 0.91 g • Temp: Cloud top –150 °C, hot interior • Orbital radius (mean) 9.58 AU • Saturnian Year: 29.7 Earth Years • Saturnian Day: 10.6 hours Saturn, from Voyager Mostly hydrogen, helium, some sulfur Saturn Rings, from Cassini

39. Saturn, from Hubble Space Telescope

40. Mostly hydrogen, helium, some methane #7 Uranus Blue-green and tilted • Discovered 1781, first planet discovered with a telescope. • Diameter: 4.0 Earths • Mass: 14.5 Earths • Density: 1.27 g/cm3 • Gravity: 0.89 g • Temp: Cloud top –220 °C, cold interior • Orbital radius (mean) 19.2 AU • Uranian Year: 84.3 Earth Years • Uranian Day: 17.2 hours Uranus, from Hubble Uranus, from Voyager 2

41. Uranus • Spins on axis tilted 98° from perpendicular.

42. #8 Neptune Blue planet • Discovered 1846, influences Uranus orbit. • Diameter: 3.8 Earths • Mass: 17 Earths • Density: 1.64 g/cm3 • Gravity: 0.91 g • Temp: Cloud top –200 °C, hot interior • Orbital radius (mean) 30.1 AU • Neptunian Year: 165 Earth Years • Neptunian Day: 16.1 hours Mostly hydrogen, helium, some methane

43. Virtually no atmosphere Pluto (now, a Dwarf Planet) • Discovered 1930, due to suspected influence on orbits of Uranus and Neptune, by Clyde Tombaugh, Lowell Observatory, Flagstaff, AZ. • Diameter: 0.2 Earths (smaller than the Moon) • Mass: 0.0021 Earths • Density: 2.0 g/cm3, rock and ice. • Gravity: 0.06 g • Temp: –230 °C Artist Concept • Orbital radius (mean) 39.5 AU. • Plutonian Year: 248 Earth Years. • Plutonian Day: 9.4 hours.

44. Pluto Images Motion observed by Clyde Tombaugh

45. New Horizons Spacecraft • Velocity approximately 16,000 mi/hr (4.4 mi/s). Launched January 2006. • Encounter July 2015. Location Today. • As it approaches Pluto, will take about 9 hours for round trip radio communications—Earth to Pluto/New Horizons.

46. Sun Charon