Structure of a Comet Ion Tail Dust Tail Coma To Sun
Comet Structure • Nucleus • 10 km “Dirty Snowball” • Coma • 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 (the furthest point away from the Sun) 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.
Comet Halley 1910 • Pope Callixtus III excommunicated Halley's Comet in 1456 • In 1910, charlatans sold "comet pills" Orbit
The Cause of Meteor Showers P55/Tempel-Tuttle
Midnight Rotational Velocity Orbital Velocity Why After Midnight is Best
Irons Stony-Irons Carbonaceous Chondrite Chondrites Achondrite Sporadic Meteors
Barringer’s Crater Iron Meteorite 100 feet across and 70,000 tons Slammed into the Earth at about 43,000 mph Arizona desert near Flagstaff 40,000 years ago. Barringer Crater is 4,100 feet wide and 571 feet deep.
Asteroids Apollo Trojans