A Crowded Solar system?• Maybe…

Not so fluffy fluff…

Solar System Fluff

A Crowded Solar system?• Maybe…

Approximate number of asteroids ‘N’ larger than diameter ‘D’

D 100 m 300 m 500 m 1 km 3 km 5 km 10 km 30 km 50 km 100 km 200 km 300 km 500 km 900 km

N 25,000,000 4,000,000 2,000,000 750,000 200,000 90,000 10,000 1,100 600 200 30 5 3 1

• 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.

• Area = Pi * (8x108)2 - Pi * (2x108)2

= 2.05 x 1018 km2 - 1.2566 x 1017 km2

= 1.885 x 1018 km2

= 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 1015 km3

•Average distance from asteroid to asteroid =

• (2.64 x 1015 km3)1/3

• = ~140000 km

Quick Volume Calculations

View From An Asteroid

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”

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

Differentiation• Differentiation occurs when

material accretes

• Compression and radiogenic decay produces heat

• The Planetesimal melts

• Dense material (metals) sink to the core

• The planetesimal may collide

• Fragments become different types of meteoroids/asteroids

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?

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…

Why are the Irons so easy to find?

• Think about it…

vs.

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

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

A meteorite hunters paradise!

A REMINDER about terminology!• Meteoroid – Meteor – Meteorite.

• Space – Atmosphere – Ground.

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

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.

IT’S OVER!!!

Radioactive Dating

• It works.