Astronomy 101 The Solar System Tuesday, Thursday Tom Burbine tomburbine@astro.umass

1. Astronomy 101The Solar SystemTuesday, ThursdayTom Burbinetomburbine@astro.umass.edu

2. Course • Course Website: • http://blogs.umass.edu/astron101-tburbine/ • Textbook: • Pathways to Astronomy (2nd Edition) by Stephen Schneider and Thomas Arny. • You also will need a calculator.

3. Final • May 7th • Friday • 4 pm • Totman Gym • Cumulative • Review Session • Hasbrouck 20, 6:15 pm, Wednesday (May 5th)

4. Formulas • p2 = a3 • F = GMm/r2 • F = ma • T (K) = T (oC) + 273.15 • c = f* • E = h*f • KE = 1/2mv2 • E = mc2 • Density = mass/volume • Volume = 4/3r3

5. HW • Homeworks #21, #22, #23, and #24

6. Uranus

7. Uranus • Discovered by William Herschel in 1781 • In 1977, the first nine rings of Uranus were discovered

9. Atmosphere • The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons. • Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green color.

10. Unusual • Tipped on its side • Why?

11. Probably • Due to a collision

12. Cordelia Ophelia Bianca Cressida Desdemona Juliet Portia Rosalind 2003U2 Belinda 1986U10 Puck 2003U1 Miranda Ariel Umbriel Titania Oberon 2001U3 Caliban Stephano Trinculo Sycorax 2003U3 Prospero Setebos 2002U2 Uranus’ Satellites

13. Instead of being named after people from classical mythology, Uranus' moons take their names from the writings of William Shakespeare and Alexander Pope.

14. Neptune

15. Neptune • After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. • It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. • Neptune was first observed by Johan Galle and Heinrich d'Arrest on 1846 Sept 23 very near to the locations predicted from theoretical calculations based on the observed positions of Jupiter, Saturn, and Uranus.

16. Galileo • Galileo's astronomical drawings show that he had first observed Neptune on December 27, 1612, and again on January 27, 1613; • On both occasions Galileo had mistaken Neptune for a fixed star

17. Neptune's blue color is largely the result of absorption of red light by methane in the atmosphere

18. Great Dark Spot • Thought to be a hole Scooter Small dark spot

19. Great Dark Spot has disappeared

20. Neptune’s Rings

21. Triton • Largest moon of Neptune • Has retrograde orbit (orbits the planet in the opposite direction as the planet is rotating) • May be captured Kuiper Belt Object

22. Pluto • Pluto is a Dwarf Planet • Smallest planet • Diameter = 2306 ± 20 km (18% of Earth) • Mass = (1.305±0.007)×1022 kg (0.0021 Earths)

24. In the late 19th century, astronomers started speculating that Neptune's orbit was being disturbed by another planet.

25. Pluto was discovered after an extensive search by Clyde Tombaugh at the Lowell Observatory in Arizona in 1930

26. Pluto • Venetia Burney (born 1919) was the first person to suggest the name Pluto for the 9th planet

27. However • Pluto is far too small to have the effect on Neptune's orbit that initiated the search. • The discrepancies in Neptune's orbit observed by 19th century astronomers were due instead to an inaccurate estimate of Neptune's mass.

28. Pluto’s orbit is exceptional among the planets • high inclination (>17 °) and eccentricity (~0.25). • Only Mercury's orbit shows a significant inclination (~7°) and eccentricity (~0.2) • Other planets follow quasi-circular, near–ecliptic orbits

30. Density • 2.03 g/cm3 • What does this mean?

32. Satellites • Charon • discovered in 1978 by astronomer James Christy • Two smaller, provisionally designated ones • Nix • Hydra

36. Barycenter (center of mass) lies above the planet's surface. • Charon is large relative to Pluto • Diameter is half of Pluto • Some astronomers label it a double planet system

39. Pluto's icy surface is 98% nitrogen (N2). • Methane (CH4) and traces of carbon monoxide (CO) are also present. • The solid methane indicates that Pluto is colder than 70 Kelvin.

40. Pluto

41. Pluto

42. Kuiper Belt • Pluto is thought to be one of the largest Kuiper Belt Objects (KBOs)

43. Kuiper Belt is a region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 55 AU from the Sun • Over 1,000 Kuiper Belt Objects (1,130) are known

45. Eris • It has a moon - Dysnomia • Larger than Pluto

46. Eris

47. New Horizons

49. Mission • Will characterize the global geology and morphology of Pluto and its moon Charon • Map their surface composition and characterize Pluto's neutral atmosphere and its escape rate • Will also photograph the surfaces of Pluto and Charon.

50. Earth • Is the only planet known to have life