Overview

2. Near Earth Objectsand Other Small Bodiesin the Solar SystemPresented toSandhills Astronomical SocietyFayetteville, NCFebruary 13, 2008Tony Vaughn

3. Overview • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

4. What is an Asteroid, Anyway? • Major Bodies • Sun • Planets • Minor Bodies • Natural Satellites • Comets • Asteroids • Meteoroids • Dust

5. International Astrophysical Union • Founded in 1919. • Composed of professional astronomers from around the world at the PhD level and above, actively engaged in research or education. • Mission: to promote and safeguard the science of astronomy in all its aspects through international cooperation. • Holds General Assembly Meetings every 3 years.

6. General Assembly XXVI, Prague, Aug 2006 Resolution B5 In our solar system: • A planet is a celestial body that • Is in orbit around the sun, • Has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and • Has cleared the neighborhood around its orbit.

7. General Assembly XXVI, Prague, Aug 2006 Resolution B5 (continued) (2) A “dwarf planet” is a celestial body that • Is in orbit around the sun, • Has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, • Has not cleared the neighborhood around its orbit, and • Is not a satellite.

8. General Assembly XXVI, Prague, Aug 2006 Resolution B5 (continued) (3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies.” These currently include most of the solar system asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

9. In Short . . . • Small bodies are either comets or asteroids • A comet is a small body that sometimes has a coma. • An asteroid is a small body that has no atmosphere or outgassing. • (An asteroid might sometimes be a depleted comet.) • An asteroid is larger than a meteoroid (10m)

10. In Short . . . An asteroid is a big rock in space.

11. Some Examples • 1 Ceres 1801 Palermo • 2 Pallas 1802 Bremen • 3 Juno 1804 Lilienthal • 4 Vesta 1807 Bremen • 5 Astraea 1845 Driesen • 6 Hebe 1847 Driesen • 7 Iris 1847 London • 8 Flora 1847 London • 9 Metis 1848 Markree • 10 Hygeia 1849 Naples . . . • 5000 IAU 1987 Palomar

12. Statistics • As of January 24, 2008: • 744,278 Registered Asteroids • 173,116 Numbered Asteroids • 14,299 Named Asteroids

13. Composition of Asteroids • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

14. Taxonomy • C-Class • Carbonaceous • S-Class • Silicaceous • M-Class • Metallic

15. Distribution of Asteroids • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

16. Distribution in the Solar System • Inner Solar System • Main Belt • Outer Solar System

17. Inner Solar System

19. Outer Solar System

20. Nomenclature of Asteroids • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

21. Nomenclature • Responsibility • Individual Asteroids • Provisional Designation • Permanent Designation • Some Examples References: http://www.cfa.harvard.edu/iau/info/OldDesDoc.html http://www.iau.org/MINOR_PLANETS_NAMING.245.0.html

22. Responsibility • Minor Planet Center (MPC) at the Smithsonian Astrophysical Observatory (SAO), under Division III of the IAU. • Central Bureau for Astronomical Telegrams (CBAT), under Commission 6 of the IAU. • Harvard University, Cambridge, MA

23. Reporting • Minor Planet Circulars (monthly) • Minor Planet Circulars Orbit Supplement • Minor Planet Circulars Supplement • Minor Planet Electronic Circulars (daily)

24. Individual Asteroids • MPC assigns a provisional designation to newly discovered asteroids • Body must have been observed for at least two separate nights. • Body must be distinct from existing lists of known bodies.

25. Provisional Naming Format • Two parts: date of discovery + serial number • Date indicates year and half month: YYYY X • Four digit year • Letter, A-Y, for half month (12 mos x 2 = 24 characters) , no I, Z • Serial number is numerical, but expressed in a mixed base, and reversed order. • An alphabetic character ranging A-Z (excluding I) • An optional number starting at 1, increasing w/o bound. Example: 2007 TA1 (= 2007 TA1) = 26th object discovered during the first two weeks of October, 2007.

26. January A B February C D March E F April G H May J K June L M July N O August P Q September R S October T U November V W December X Y Date Codes Second half of the month begins on the 16th. Some older asteroids used I in place of J, but modern usage replaces the I with the standard J.

27. Serial Number • Think “Place Value,” but in base 25. • Designation has two “places,” one in base 25, the other in infinite base, but represented as base 10 (decimal). • LSB is one alphabetic character {A=0, Z=24} • MSB is numeric • To convert to a normal decimal number, N: N = MSB x 25 + LSB + 1 e.g.: 2007 TU24 N = 24 x 25 + U{=19} + 1 = 620

28. Permanent Designation • Assigned when orbit is determined to acceptable predictability (normally two or more full periods). • Simple serial number. • In addition, discoverer is invited to suggest a name, to be approved by the Committee on Small Body Nomenclature (CSBN).

29. Three names: Provisional: 1929 CD Permanent: 1664 Unique Name: Felix Fourth discovery in February 1929 by E. Delporte at Uccle, BE Combined designation: (1664) Felix Also known as 1936 AD 1947 FC 1949 WC 1954 DD 1956 TV 1961 AE An Example

30. 243 Ida

31. 45 Eugenia

32. 216 Kleopatra

33. 433 Eros

34. NEAR at 433 Eros

35. Near-Earth Asteroids • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

36. Classification by Orbital Elements • Orbital Elements Overview • Orbit Size and Shape • Orbital Neighborhood • Orbital Relationships

37. Orbital Elements Overview

38. Orbit Size and Shape

39. Orbit Size and Shape

40. Neighborhood of a Planet

41. Neighborhood of a Planet

42. Neighborhood of a Planet

43. NEOs and PHAs • Near Earth Objects • Semi-major axis < 1.3 AU • Potentially Hazardous Asteroids • MOID < 0.05 AU • Diameter > 150 m

44. Atiras Orbit inside Earth’s orbit a < 1 AU Q < 0.983 AU Atens Aphelion within Earth’s orbit a < 1 AU Q > 0.983 AU Apollos Perihelion within Earth’s orbit a > 1 AU q < 1.017 AU Amors Orbit outside Earth’s orbit a > 1 AU 1.017 < q < 1.3 AU Families of NEOs

45. Earth Schematic: Aten Aten a < 1 AU Q > 0.983 (Earth’s q )

46. Earth Schematic Apollo Apollo a > 1 AU q < 1.017 (Earth’s Q )

47. Earth Schematic Amor Amor a > 1 AU 1.3 > q > 1.017 AU (Earth’s Q )

48. Observation of Asteroids • Definition • Composition • Distribution • Nomenclature • NEOs and PHAs • Observation

49. Observation • Plan Ahead • Use a Star Chart • Identify nearby stars at several scales • Plot “rulers” visually • Make drawings or take photos

50. Astronomical League • Asteroid Observing Club • Regular Member • Gold Member • Requirements • 25 (100) asteroids • Observed at least twice • Sketches or photos • Receive certificate (and pin)