Asteroids Meteroids and CometsOh my Asteroids u u

Asteroids, Meteroids, and Comets…Oh my!

Asteroids u u Asteroids – A rocky lump of frozen gas that can range in size from a few hundred feet to several hundred miles wide. Matter that is similar in composition to the planets. Sometimes, it’s called a Planetoid. Orbit in a belt between Mars and Jupiter. Largest asteroid known: Ceres (1801)

u Asteroid Gaspra – photographed by the Galileo spacecraft in 1991.

What prevents the Asteroids in the belt from plunging into the sun and hitting the inner planets in the process? u The Sun’s gravity and Jupiter’s gravity!

Meteoroids – Small fragments of matter, like rock, stone, and metals (smaller than asteroids) that orbit the sun at a variety of speeds; pieces of planets, moon, or asteroids u Meteor - “shooting star” u • This happens when a meteoroid enters Earth’s atmosphere and begins to burn. • Briefly visible • Fireball – Long streaks of bright light created by these racing meteors

Fireball from a meteor in the night sky. u Pennsylvania 1992 u

Sometimes meteors strike Earth! u Meteorite – a meteor that impacts the ground. • Most meteorites fall into the oceans. • Most meteorites fall to earth as dust, because they burn up in the atmosphere. • “Micrometeorites” strike Earth daily. These can be as small as pebbles. • Size of a mountain every 10, 000 years. • Craters are created when large meteorites strike a moon or planet. u 3 km wide in Quebec, Canada

u u Largest Meteorite to strike US – Oregon 1902 1954 – crashed through the living room and injured a woman.

What’s the difference between a meteoroid, meteor, and meteorite? u u u Meteoroid – still in space Meteor – enters earth’s atmosphere Meteorite – meteor that strikes earth because it’s so big it doesn’t burn up. Seen during a football game. Pieces of it crashed into the trunk of a parked car.

Meteor Shower The 1966 Leonids Meteor Shower u Arizona; 2300/minute for 20 minutes u

Comets u u u Comets – lumps of frozen gas and rock that orbit the sun in a highly eccentric way. A heavenly body that is usually named after its discoverer. Believed to originate in an Oort cloud. (Huge cloud that is thought to surround our solar system). Nucleus – the center of a comet. Coma – large halo of gas and dust that forms around the nucleus of a comet when it gets close to the sun. It actually loses mass as it gets close to the sun.

More about a comet u u u Comets orbit the sun in an elliptical pattern. Comets have tails. Their tails are made of frozen gases, cosmic dust, and rocky particles. As a comet travels toward the sun, its head leads the way. But as it travels away, its tail leads the way. This is due to Solar winds. Haley’s comet – a space curiosity that returns to Earth’s view every 76 years.

Haley’s Comet u u It has been spotted for thousands of years. Sir Edmond Halley – English astronomer (1656 -1742)

Can you find Haley’s Comet in the tapestry below dated from 1066 A. D. ?