News 8 Wednesday, July 10, 2013 Orange County Register 1 ASTRONOMY A LUNAR ROLL CALL There are a total of 146 moons in our solar system with another 25 awaiting official recognition by the International Astronomical Union. NASA’s official list of moons: EARTH MARS 1. Moon 1. Phobos MOONS 2. Deimos JUPITER It’s nice to know that whatever planet you visit — with the 1. Io 26. Isonoe exception of sun-drenched Mercury and Venus — you’ll find a 2. Europa 27. Praxidike 3. Ganymede 28. Autonoe gorgeous moon hitting your eye like a big pizza pie. Here’s a look at 4. Callisto 29. Thyone 5. Amalthea 30. Hermippe some of our solar system’s notable natural satellites: 6. Himalia 31. Aitne 7. Elara 32. Eurydome 8. Pasiphae 33. Euanthe 9. Sinope 34. Euporie Larger than Mercury and Pluto, Gany- 10. Lysithea 35. Orthosie GANYMEDE mede is three-quarters the size of Mars. 11. Carme 36. Sponde The surface of Ganymede is mostly ice, 12. Ananke 37. Kale NASA says, but with some rock thrown Orbits: 13. Leda 38. Pasithee Jupiter in. Deep grooves called “slucus” run Diameter: 14. Thebe 39. Hegemone 3,270 miles across the surface, yet the craters have 15. Adrastea 40. Mneme Discovered: 1640 little depth to them. Ganymede has an 16. Metis 41. Aoede by Italian astronomer oxygen atmosphere, but far too thin to 17. Callirrhoe 42. Thelxinoe Galileo Galilei support life as we know it. 18. Themisto 43. Arche 19. Megaclite 44. Kallichore 20. Taygete 45. Helike Titan is the only moon in the solar 21. Chaldene 46. Carpo TITAN system known to have clouds and a 22. Harpalyke 47. Eukelade thick, planet-like atmosphere. The 23. Kalyke 48. Cyllene atmosphere is mostly nitrogen but with Orbits: 24. Iocaste 49. Kore Saturn methane and ethane present. NASA 25. Erinome 50. Herse Diameter: 3,202 miles speculates that the rain there could be Discovered: 1655 “gasoline-like” liquids. Air pressure on PROVISIONAL MOONS by Dutch astronomer Titan’s surface is roughly the same 51. S/2003 J2 59. S/2003 J16 Christiaan Huygens found at the bottom of a swimming pool. 52. S/2003 J3 60. S/2003 J18 53. S/2003 J4 61. S/2003 J19 54. S/2003 J5 62. S/2003 J23 Nearly the size of Mercury, Callisto is 55. S/2003 J9 63. S/2010 J 1 CALLISTO the most heavily-cratered object in the 56. S/2003 J10 64. S/2010 J 2 solar system. NASA considers it a dead 57. S/2003 J12 65. S/2011 J1 world — it’s the largest object in our 58. S/2003 J15 66. S/2011 J2 Orbits: Jupiter solar system that has no geological Diameter: 2,996 miles activity. Its orbit keeps it well outside Discovered: 1640 of Jupiter’s radiation belts and the tidal SATURN by Italian astronomer forces that give its sister moon, Io, 1. Mimas 28. Skathi Galileo Galilei volcanic life. 2. Enceladus 29. Siarnaq 3. Tethys 30. Thrymr 4. Dione 31. Narvi Io’s elliptical orbit around the enor- 5. Rhea 32. Methone IO mous planet Jupiter creates tides of 6. Titan 33. Pallene 330 feet. This results in heat that 7. Hyperion 34. Polydeuces causes Io to be the most volcanically 8. Iapetus 35. Daphnis Orbits: Jupiter active body in the solar system. Volca- 9. Erriapus 36. Aegir Diameter: 2,264 miles nic plumes rise nearly 200 miles above 10. Phoebe 37. Bebhionn Discovered: 1640 the surface. Scientists think Io is 11. Janus 38. Bergelmir by Italian astronomer mostly molten sulfur and that its 12. Epimetheus 39. Bestla Galileo Galilei atmosphere is mostly sulfur dioxide. 13. Helene 40. Farbauti 14. Telesto 41. Fenrir 15. Calypso 42. Fornjot Earth’s lone companion has no atmo- 16. Kiviuq 43. Hati MOON sphere to burn up meteors, resulting in 17. Atlas 44. Hyrrokkin the familiar rough, pockmarked surface. 18. Prometheus 45. Kari The lighter areas are mountains. The 19. Pandora 46. Loge Orbits: Earth darker areas are flatter areas where 20. Pan 47. Skoll Diameter: 2,152 miles lava pooled from no-longer-active 21. Ymir 48. Surtur volcanoes. Recent studies have 22. Paaliaq 49. Greip suggested there may be water ice 23. Tarvos 50. Jarnsaxa present at the lunar poles, NASA says. 24. Ijiraq 51. Tarqeq 25. Suttungr 52. Anthe 26. Mundilfari 53. Aegaeon Scientists think Europa contains twice 27. Albiorix EUROPA as much water as does Earth — what you PROVISIONAL MOONS see there might be a thin crust of ice covering slushy, salty ice. Europa’s 54. S/2004 S7 59. S/2006 S3 Orbits: Jupiter elliptical orbit creates strong tides, 55. S/2004 S12 60. S/2007 S2 Diameter: 1,940 miles which may explain the enormous cracks 56. S/2004 S13 61. S/2007 S3 Discovered: 1640 in the ice. These tidal forces also warm 57. S/2004 S17 62. S/2009 S1 by Italian astronomer the moon just a bit, giving scientists 58. S/2006 S1 Galileo Galilei hope that life might possibly exist there. URANUS Triton’s surface resembles a canta- 1. Cordelia 15. Francisco TRITON loupe, NASA says. Ice volcanoes spew 2. Ophelia 16. Ariel what is probably a mixture of liquid 3. Bianca 17. Umbriel nitrogen, methane and dust into the air, 4. Cressida 18. Titania Orbits: Neptune where it freezes and snows back onto 5. Desdemona 19. Oberon Diameter: 1,682 miles the surface. Triton orbits in a direction 6. Juliet 20. Caliban Discovered: 1846 opposite Neptune’s rotation. As a 7. Portia 21. Stephano by English astronomer result, the moon is gradually slowing 8. Rosalind 22. Trinculo William Lassell and dropping closer to the surface. 9. Mab 23. Sycorax 10. Belinda 24. Margaret 11. Perdita 25. Prospero Compared to the other moons on this 12. Puck 26. Setebos MIMAS list, Mimas is tiny. But it’s famous for 13. Cupid 27. Ferdinand an obvious reason: That enormous 14. Miranda crater — 88 miles across and with walls Orbits: Saturn three miles high — makes this moon look NEPTUNE Diameter: 246 miles a lot like the Death Star space station Discovered: 1789 in the “Star Wars” movies. Mimas’ orbit 1. Triton 8. Proteus by English astronomer is thought to be responsible for gaps 2. Nereid 9. Halimede William Herschel and lumps in some of Saturn’s rings. 3. Naiad 10. Psamathe 4. Thalassa 11. Sao 5. Despina 12. Laomedeia Source: NASA’S Jet ALL IMAGES FROM NASA AND NASA’S COMPILED BY CHARLES APPLE, 6. Galatea 13. Neso Propulsion Laboratory JET PROPULSION LABORATORY ORANGE COUNTY REGISTER 7. Larissa.