Meteors A streak of light ( a “shooting star”0 that suddenly appears in the sky when a particle from a comet or asteroid enters the Earth’s atmosphere Most meteors occur in the region of the atmosphere called the thermosphere. This “meteoric region” lies between about 80 km and 120 Km in altitude.

Meteor Terminology Comet—a solid body made of ice, rock, dust, and frozen gases. As they fracture and disintegrate, some comets leave a trail of solid debris Asteroid---amall rocky, iron, or icy debris flying in space Meteoroid---a small asteroid Meeor Shower---an annual event, when Earth passes through a region having a great concentration of debris, such as particles left by a comet. From Earth, it looks like meteors radiate from the same point in the night sky.

Meteor Terminology Meteor---the light emitted from a meteoroid or an asteroid as it enters the atmosphere Fireball—a meteor brighter than the planet Venus Bolide---the light emitted by a large meteoroid or an asteroid as it explodes in the atmosphere Meteorite---a fragment of a meteoroid or an asteroid that survives passage through the atmosphere and hits the ground

Meteorite A fragment of a comet or asteroid that survives its passage through the Earth’s atmosphere and lands on the Earth’s surface The Barringer Meteorite Crater in Arizona, about 0.6 miles across, is only 50,000 years old and so well preserved that it has been used to study impact process

Meteorite Three types -----Iron -----Stony ------Stony-iron composition Most meteorites formed 4.55 billion years ago November 30 1954—Ann Hodges is severely bruised by an 8 lb. stony meteorite when it crashes through her roof in Sylacauga, Alabama. ( The only person to have ever been injured by a meteorite.)

Meteorite Meteorites may resemble Earth rocks, but they usually have a burned exterior. This fusion crust is formed as the meteorite is melted by friction as it passes through the atmosphere. Majority of meteorites that fall are irons- these heavy objects are easier to distinguish from Earth rocks than stony meteorites. More than 50,000 meteorites found on Earth- 99.8% come from asteroids

Asteroids small, rocky solar system bodies that populate interplanetary space out to the orbit of Jupiter. Millions—often grouped by composition Refered to by scientist as minor planets Minor planets—solar system bodies smaller that moons Mainly made of materials left over from the formation of the inner solar system worlds

Asteroids Most orbit Sun between Mars and Jupiter (Asteroid Belt) Three Composition classes ------------C-types (chondrites)—made of clay and silicate rocks -------------S-types---stony asteroids and are made mostly of silicate rocks and nickel-iron mixtures --------------M-types—metalic nickel-iron These categories indicate how far from the Sun they formed in the early solar system.