1. Asteroids
Kailyn Derck

2. Background
Giuseppe Piazzi discovered an object which he first thought was a new comet on January 1, 1801
Piazzi named it Ceres, after the Sicilian goddess of grain.
The surface of an asteroid is filled with big and small rocks

3. Asteroids are classified into a number of types according to their spectra and chemical composition
Most lie between Mars and Jupiter
About 50,000 are about 1 km across
The biggest, Ceres, is 1000 km across
All together, the asteroids equal about 1/1000 of the Earth’s mass and do not total the moon’s mass

4. Asteroids are also categorized by their position in the solar system:
Main Belt: located between Mars and Jupiter
Near-Earth Asteroids (NEAs): ones that closely approach the Earth
Trojans: located near Jupiter’s Lagrange points - 60 degrees ahead and behind Jupiter in its orbit Several hundred such asteroids are now known; it is estimated that there may be a thousand or more altogether.

5. Impact
About 65 million years ago an asteroid hit the earth near the Gulf of Mexico, Yucatan Penninsula
70 percent of all species perished in a mass extinction
Thought to be the extinction of the dinosaurs
Dust and dirt in the air caused vegetation to die

6. Impact The moon’s craters were caused by asteroids
The Earth does not have as many visible signs due to weathering
Small asteroid caused Barringer Meteor Crater, Arizona: 49,000 years old and .737 miles across

8. Impact
NASA says there is no reason to believe an asteroid will hit again soon
Very large asteroids hit the earth once in every 100 million to 1 billion years
Large ones hit once every 100 million years