Comets, Meteors, and Asteroids

Structure of a Comet Ion Tail Dust Tail Coma To Sun

Comet Structure Nucleus Coma Tail 10 km “Dirty Snowball” Cloud of evaporated ices and ions may be 100,000 km in diameter Tail Always 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 Tapestry Norman Invasion of 1066

164 BCE, Babylon

Comet Nucleus

Comet of 1577

Hale-Bopp

Comet West

The Cause of Meteor Showers P55/Tempel-Tuttle

Why After Midnight is Best Orbital Velocity Rotational Velocity

The 1833 storm

The 1966 storm

1997 Leonids from Orbit

Two Showers for Halley

Carbonaceous Chondrite 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

Asteroids Elsewhere

Asteroid: A relatively small, inactive body, composed of rock, carbon or metal, which is orbiting the Sun. Comet: A relatively small, sometimes active object, which is composed of dirt and ices. Comets are characterised by dust and gas tails when in proximity to the Sun. Far from the Sun it is difficult to distinguish an asteroid from a comet. Meteoroid: A small particle from an asteroid or comet orbiting he Sun. Meteor: A meteoroid that is observed as it burns up in the Earth's atmosphere - a shooting star. Meteorite: A meteoroid that survives its passage through the Earth's atmosphere and impacts the Earth's surface.