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Pluto and Kuiper Belt

Pluto and Kuiper Belt. Lecture 26. Discovery of Pluto. Like Neptune’s influence on Uranus’ orbit, in late 19 th century, many astronomers believed that Neptune’s orbit was also perturbed by an unseen (yet-to-be-discovered) planet. Percival Lowell installed a wide-field camera in 1929.

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Pluto and Kuiper Belt

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  1. Pluto and Kuiper Belt Lecture 26

  2. Discovery of Pluto • Like Neptune’s influence on Uranus’ orbit, in late 19th century, many astronomers believed that Neptune’s orbit was also perturbed by an unseen (yet-to-be-discovered) planet. • Percival Lowell installed a wide-field camera in 1929. • in 1930, Clyde Tombaugh discovered an object beyond Neptune’s orbit but 250 times fainter! Method of discovering planets

  3. Pluto • Pluto’s orbit is very different from those of other planets • eccentricity = 0.25  sometimes, Pluto gets closer to the Sun than Neptune! • inclination = 17.15° • Pluto is so far away, and its apparent diameter is only 0.15 arcsecond  makes it harder to understand Pluto even in the 21st century.

  4. Image of Pluto

  5. Observation of Solar System objects Unlike observations of far away stars, they move even over a short duration of few minutes! Different tracking of telescope is needed!

  6. Pluto’s satellite, Charon Separation is only 19,640km (5% of the Earth-Moon distance)  6.4 days of orbit impact origin of Charon?

  7. Pluto in the Sky If Pluto and Charon were created from a collision of two large rocks, there should be a large population of similar objects near (or beyond) Neptune’s orbit.  Search began.

  8. Discovery of KBOs • Discovery image of 1992 QB1 (1992 Aug 30) by Dave Jewitt • First object beyond Pluto’s orbit = Kuiper Belt Object = Trans-Neptunian Object

  9. Another KBO : 1993 SC • This image is shows a small part of the discovery frames of 1993 SC, one of the brightest Kuiper-Belt objects so far discovered. It was taken using the 2.5m Isaac Newton Telescope on La Palma by Alan Fitzsimmons, Iwan Williams and DonalO'Ceallaigh on 17th September 1994. The two images are separated in time by 4.6 hours, and by comparing them it is clear that one of the objects has moved from upper left of center to almost merging with the image of a distant galaxy. This motion marks it as being a distant member of our solar system, further away than the planet Neptune.

  10. Quaoar : “Kwawar” • Discovered by Chad Trujillo and Michael Brown in 2002. … and the quest for larger, more distant KBOscontunued…

  11. Binary KBOs

  12. 2003 UB313 = “Xena” = Eris Discovered by M. Brown + Even larger than Pluto (by ~30%).

  13. Haumea Why is Haumea shaped like a potato? Although the dwarf planet has never been directly observed, its elongated shape has been calculated from its light curve. Haumea’s length is twice that of its width. Discovery conspiracy b/w Caltech and Spanish team: - discovered in Dec 2004 from an image on May 6, 2004 - Spanish team reported a discovery of on July 2005 from an image taken on Mar. 2003

  14. Currently known KB objects About 500 known KBOs

  15. A slew of new discoveries… Larger (or similar) objects kept discovered even at larger distances… They are similar in size and composition. What should we call them?

  16. Orbit of Sedna Starting at the inner Solar System, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green).

  17. Dwarf planets 'planet' gets more press attention than 'large Kuiper belt object’ Plutons: suggested by the IAU before they realized that this is a well-established geological term for an intrusive rock mass. Plutoids: suggested by some astronomers. Dwarf Planets : the IAU's half-way suggestion. Not a real planet, but still has 'planet' in the name, like 'minor planets' (a.k.a asteroids).

  18. Dwarf Planet • Accepted in the IAU meeting in 2006 from the pressure of ever-increasing number of Trans-Neptunian objects Planet: • an object orbiting the Sun (i.e., no satellites) • massive enough to be spherical (large enough gravity) • cleared its neighboring region (i.e., no embedded large asteroids) Dwarf Planet: • an object orbiting the Sun • sufficient mass to be round-shaped (or nearly) • has not cleared its surrounding region • not a satellite Small Solar System Bodies: all other objects except satellites. Strongest objections  school teachers and astrologers (and some US Astronomers)…

  19. Dusty Disks • KBOs collide among themselves and create a myriad of small dust grains • Breaking on 100km object into 1micron particles  1027 particles • increase the surface area by billion times • a disk is billion times easier to discover than a large KBO around other star This disk of dust grains is known as Debris Disk  disk made of debris of planet formation

  20. Astronomy Picture of the Day 2010 September 13 An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually zodiacal light, light reflected from interplanetary dust particles. The bright reflecting triangle is clearly visible on the right of the above horizontally-compressed image taken just after sunset from Namibia in the southern hemisphere in 2009 June.

  21. Imaging Debris Disks with Coronagraph Using coronagraph, images of dozens of debris disks were obtained (mostly with Hubble Space Telescope).

  22. Some images of Debris Disks

  23. Debris Disks are signposts of exoplanetary systems

  24. Outermost edge of the Solar System Oort Cloud Kuiper Belt Objects

  25. In summary… Important Concepts Important Terms Trans-Neptunian Objects Kuiper Belt Objects Dwarf Planets Zodiacal light • Relation between KBOs and Debris Disks • Definition of IAU Planet • Reasons behind the name of “Dwarf Planets” • Chapter/sections covered in this lecture : sections 14-9 and 14-10

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