minor bodies

Comets, Meteors, and Asteroids

Structure of a Comet

To Sun

Ion Tail

Dust Tail

Coma

Comet Structure

Nucleus10 km “Dirty Snowball”

ComaCloud of evaporated ices and ionsmay be 100,000 km in diameter

TailAlways points away from Sun

Solar Wind and Radiation Pressure

The Oort Cloud

In 1950 Jan Oort noticed that no comet has been observed with an orbit that

indicates that it came from interstellar space,

there is a strong tendency for aphelia of long period comet orbits to lie at a distance of about 50,000 AU, and

there is no preferential direction from which comets come.

The Oort Cloud

Comet Halley

Bayeaux TapestryNorman Invasion of 1066

Comet Halley 1910

•Pope Callixtus III excommunicated Halley's Comet in 1456

•In 1910, charlatans sold "comet pills"

Orbit

Comet Nucleus

Comet of 1577

Hyakutake

Hale-Bopp

Comet West

The Cause of Meteor Showers

P55/Tempel-Tuttle

Why After Midnight is Best

Rotational Velocity

Orbital Velocity

Midnight

Shower Radiant

The 1833 storm

The 1966 storm

1997 Leonids from Orbit

Two Showers for Halley

Sporadic Meteors

Irons Stony-Irons

Chondrites Carbonaceous Chondrite

Achondrite

Barringer’s Crater

An iron meteorite 100 feet across and 70,000 tons slamed into the Earth at about 43,000mph in the Arizona desert near Flagstaff 40,000 years ago. Barringer Crater is 4,100 feet wide and 571 feet

deep.

Other Impact Craters

Tunguska, 1908

How Much Damage?

Asteroids

Apollo

Trojans

Ida - Dactyl

Gaspra

Kirkwood Gaps

Asteroids Elsewhere

Sedna

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