Comets, Meteors, and Asteroids

Comets  The word "comet" comes from the Greek word for "hair.”  Our ancestors thought comets were stars with what looked like flowing hair trailing behind.

Structure of a Comet To Sun Ion Tail Dust Tail Coma Comets: “Dirty Snowballs”  Comets are loose collections of ice, dust, and small rocky particles whose orbits are usually very long, narrow ellipses.

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  Dust and Ion Tails

Comet’s Orbit  Comets move in an elliptical shaped orbit.

Where do comets come from? The Oort Cloud & The Kuiper Belt

Comet Halley

Bayeaux Tapestry Norman Invasion of 1066

Comet Halley 1910 Pope Callixtus III excommunicated Halley's Comet in 1456 In 1910, charlatans sold "comet pills"

Comet Nucleus

Comet of 1577

Hyakutake

Hale-Bopp

Comet West

What does a comet leave behind? Meteoroids

What happens when Earth travels through the remains of a comet’s tail?

Meteriods burn up in our Atmosphere Then we call them METEORS OR in this case… A METEOR SHOWER

After Midnight is Best to view meteors…or meteor showers Rotational Velocity Orbital Velocity Midnight

The 1833 storm

1997 meteors from Orbit

Two Showers for Halley in the same year

Sporadic Meteorites IronsStony-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

But when they cause this much damage…they are usually called ASTEROID COLLISIONS

Asteroids……Rockin’ Around Asteroids are LARGE chunks of rock and metal that orbit the sun. They range from just over ½ a mile (1km) to a few hundred miles in diameter (diameter = how wide across)

Asteroids……Rockin’ Around Most of the chunks or rock and metal in space came together long ago to form the planets and moons. Asteroids are left-over pieces of rock from when the solar system was formed.

Asteroids……Rockin’ Around Most asteroids travel in the wide gap between the inner planets and outer planets (between Mars and Jupiter). But a few travel in paths across Mar’s orbit and some even cross in Earth’s orbit.

Asteroids

Ida - Dactyl

Gaspra

Asteroids Elsewhere

Sedna

What’s That Up In The Sky??? COMETSASTEROIDSMETEOROIDSMETEORS Made of ice-have tails Large; Made of rock and metal Smaller: Made of rock and metal Stay in space Fall into Earth’s atmosphere Orbit the sun Gravity pulls to Earth; they burn up as they fall