Discoveries of Planets Pluto Asteroids Comets Meteoroids Meteors Meteorites Meteor Showers

2. Discoveries of Planets Pluto Asteroids Comets Meteoroids Meteors Meteorites Meteor Showers

3. + + + ¤ William Herschel 1781 Found Fuzzy Thing in Sky Moved Three Positions Orbit Elongated Comet Circular Planet Uranus

4. ¤ 50 Years Later Not Following Predicted Orbit Perturbed Perturbation Undiscovered Planet Observed by Galileo Credit for Discovery Only After Repeated Sightings 1846 Leverrier Neptune Uranus

5. Perturbations Percival Lowell Planet X Clyde Tombaugh 1930

8. ¤ announcement delayed Percival Lowell’s birthday general position given skepticism orbit calculation Stanford very eccentric orbit comet? Flagstaff Object prediscovery photo 1915 better orbit

9. Mass From Perturbations Comparable to Earth Size From Brightness and Distance Comparable to Earth

10. Brother of Jupiter Both his brothers have planets. Ruler of Hades A Cold Dark Place Pluto is cold and dark because it’s far from the sun. Visibility Pluto, the god, has a helmet of invisibility. The high eccentricity means it will sometimes be close and bright, but also far and dim.

11. m Occultation 1955

12. Mass From Perturbations Comparable to Earth Size No Occultation Much Smaller

13. Mass From Perturbations Comparable to Earth Size No Occultation Much Smaller Much Denser 33g/cm3

19. Mass From Orbit of Charon 1/500 Earth Mass Size No Occultation Much Smaller Much Denser 33g/cm3

20. What perturbed Uranus and Neptune? undiscovered planet? perturbations based on masses of Uranus and Neptune Neptune’s mass was poorly known. perturbation calculations repeated with correct mass perturbations disappear no more planets in solar system

21. 1978 Discovery Charon Eclipses Predicted 1980 Started 1985

26. Mass From Orbit of Charon 1/500 Earth Mass Size Eclipse Observations 2400 km Planet?

27. Qualifications for Planet comets asteroids 1000 km Ceres Mercury Venus orbit sun size mass moons atmosphere shape

28. Terrestrial Earth Venus Mars Mercury Moon Jovian Jupiter Saturn Neptune Uranus Plutonoid Pluto Charon 1992 QB1 1993 FW 5145 Pholus

30. m time

31. m time

34. Mass 1/500 Diameter 2400 km Density 2 g/cm3 Composition Temperature Distance From Sun 1/200 2700 km Pluto Triton

35. 3:2 1979 1999 2003 ¤

36. Asteroids Comets Meteoroids Meteors Meteorites Debris

37. Asteroids Comets Meteoroids Meteors Debris

39. Asteroids Meteors Meteorites Debris

40. Asteroids rock, glass, metal Comets ice, soot, sand, rock Meteoroids sand grains, ice, rock smaller, different origin Debris

41. parent body iron/nickel meteorites core of planet? rock & glass meteorites mantle of planet? Main Belt Mars Jupiter

42. Trojans Lagrange points named after Trojan and Greek heroes in Trojan war Apollo family cross Earth Orbit

43. more Apollos Icarus Adonis Hermes

44. more Apollos Icarus Adonis Hermes Daedalus Hephaistos Cerberus

45. ¤ Å Killer Asteroids Apollo perturbations 1997 XF11 2028 prediscovery asteroid tugboat

46. Amor family nearly Earth-crossing perturbations