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Minor Planets

Minor Planets. Between the meteorites and the moons. Dwarf Planets. A celestial body orbiting the Sun Massive enough to be spherical as a result of its own gravity Has not cleared its neighboring region of planetesimals Is not a satellite (does not orbit another planet).

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Minor Planets

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  1. Minor Planets Between the meteorites and the moons.

  2. Dwarf Planets • A celestial body orbiting the Sun • Massive enough to be spherical as a result of its own gravity • Has not cleared its neighboring region of planetesimals • Is not a satellite (does not orbit another planet). • 5 currently recognized by the IAU: Ceres, Pluto, Haumea, Makemake, and Eris. • 50 – 200 other current candidates.

  3. Asteroids • No true formal definition • Tends to refer to minor planets within the inner solar system, larger than 10 km diameter. • Can also be referred to as Planetoid or “Small Solar System Object”

  4. Trans-neptunian objects (TNO) • ANY object that is part of the solar system and beyond the orbit of Neptune. • Kuiper Belt: • Objects from 30 – 50 A.U. (KBO = Kuiper Belt Object) • Primarily Icy, with frozen volatiles (methane, ammonia, etc.) • Scattered Disc: • Sparse collection of larger TNOs, beyond the Kuiper Belt • Similar in composition to Kuiper Belt Objects • It is now believed that most comets originated from this region. • Oort Cloud: • Farthest reaches of the solar system • Spherical in structure, instead of flat, disc shaped regions

  5. The rest of the objects Boulders to Dust

  6. Comets • Highly eccentric orbits • Believed to originate from the scattered disc • Many come from the Kuiper Belt or Oort Cloud as well. • Can range from “Icy mudball” to “dirty snowball” in composition.

  7. Meteoroids • sand to boulder-sized particle of debris in the solar system • Ranges from icy to rocky to metallic • When it enters the earth’s atmosphere it becomes a METEOR • Once it lands on the surface of the earth, it becomes a METEORITE

  8. IT’S OVER!!!

  9. A Crowded Solar system? • Maybe…

  10. Solar System Fluff Not so fluffy fluff…

  11. A Crowded Solar system? • Maybe…

  12. Quick Volume Calculations • Area = Pi * (8x108)2 - Pi * (2x108)2 = 2.05 x 1018 km2 - 1.2566 x 1017 km2 = 1.885 x 1018km2 = 1,885,000,000,000,000,000 km2 • Volume = 1.885 x 10^18 km2 * 140,000 km • = 2.64 x 1023 km3 • = 264,000,000,000,000,000,000,000 km3 • Space volume PER asteroid = • 2.64 x 1023 km3/ 1.0 x 108= 2.64 x 1015km3 • Average distance from asteroid to asteroid = • (2.64 x 1015 km3)1/3 • = ~140000 km • Majority of asteroids are between Mars & Jupiter • Quick area calculation of that space to the right • Volume? • Assume that ALL asteroids are in a region no thicker than the diameter of Jupiter itself (140,000 km) • Assume 100 million (100,000,000) asteroids (not nearly that many…) • So then the average distance from one asteroid to another would be… • That’s 1/3 the distance to the moon.

  13. View From An Asteroid

  14. Differentiation • Differentiation occurs when material accretes • Compression and radiogenic decay produces heat • The Planetesimal melts • Dense material (metals) sink to the surface • The planetesimal may collide • Fragments become different types of meteoroids/asteroids

  15. What types are out there? • C - type • Rocky (silicate) with lots of carbon compounds (think charcoal) • S – type • Rocky (silicate) without the carbon compounds • M – type • Metallic (Iron & Nickel) • Why the different types?

  16. From the asteroids, Meteoroids • Stony Meteorites • Can be from C type asteroids OR S-type • Stony – Iron Meteorites (1% of all) • From unusual “boundary” asteroids • Iron Meteorites (2-3% of all) • From M type asteroids • Make up 40% of all “finds” however…

  17. Chondrites • Special meteorites – Unchanged from the beginnings of the solar system. • 4.6 billion years old (beginning of the solar system • Never accreted onto a larger body • Therefore never underwent the differentiation process • Contain chondrules • Droplets of material leftover from initial condensation of the solar nebula • Carbonaceous chondrites • Contain organic molecules • Stuff for life

  18. Why are the Irons so easy to find? • Think about it… vs.

  19. Not all are so easily categorized however… • We sometimes get splattered with debris from distant impacts.

  20. A meteorite hunters paradise!

  21. Radioactive Dating • It works.

  22. A REMINDER about terminology! • Meteoroid – Meteor – Meteorite. • Space – Atmosphere – Ground.

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