Planets and Stars

Stars• Were noticed even before telescopes.

• Balls of glowing hot gas.

• Did not change position in the night sky.

Planets• Objects that changed position from night to

night against the stars.

• Large bodies orbiting a star.

• The Sun’s gravity keeps them in orbit.

• There are 8 planets in our solar system.

Early Idea of the Solar System

• Earth did not move

• Earth was at the center of the Solar System

• The stars, Moon, and Sun revolved around Earth

Copernicus Solar System

• The Sun was at the center of the universe

• Was very unpopular when it was introduced

The Two Solar System Models

• http://www.youtube.com/watch?v=iiBIFlvu-X0&feature=related

Solar System

• The Sun and all of the planets, moons, and other bodies traveling around it.

Asteroids

• Rocky or metallic

• Orbit the Sun

• Too small to be considered a planet

• Some astronomers believe they are material that never combined to form a planet.

Asteroid Belt• Most are located between the orbits of Mars

and Jupiter

• Some travel from Saturn’s orbit, others have orbits that cross Earth’s path.

Asteroid Theories

• Was what caused the dinosaurs to become extinct.

Asteroids that have hit Earth

• http://www.meteorcrater.com/

• http://geology.com/meteor-impact-craters.shtml

• Small asteroids

• Some travel to the edge of the solar system

• Others stay within the orbits of the inner planets

Meteoroids

Where they come from

• From material ejected by a passing comet.

• From the asteroid belt

Meteors

• When a meteoroid hits Earth’s atmosphere. – The meteor rubs against Earth’s atmosphere

producing heat.– This heat causes the meteor to burn.• Try rubbing your hands together to produce heat.

• Seen as a bright streak of light.

Meteorite• Any part of a meteoroid that reaches Earth’s

surface.

• 3 types:– Stony – made out of rock– Metallic – made from metals like nickel and iron or

a mixture of metal and rock– Carbonaceous – rich in carbon

Meteor Shower

• When many meteoroids hit Earth’s atmosphere at the same time.– Often happens after a comet has traveled past Earth.

• Some occur year after year.– Perseid Meteor Shower happens around August 11

2103 Meteor Showers

• http://stardate.org/nightsky/meteors

• Perseid Meteor Shower Time Lapse:– http://

www.theguardian.com/science/video/2013/aug/13/perseids-meteor-shower-timelapse-video

• http://video.search.yahoo.com/search/video;_ylt=A2KLqIT4lFZSD0EA5c_7w8QF;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-?p=2013+perseid+meteor+shower&ei=utf-8

Comets

• A Ball of ice and rock– kind of like a dirty snow ball.

• Orbits the Sun

Parts of a Comet n

• The nucleus is the main, solid part of the comet

• The coma is a halo of evaporated gas (water vapor, ammonia, carbon dioxide) and dust that surrounds the nucleus

• The comet's dust tail always faces away from the sun.

A Comet’s Orbit• As it comes closer to the Sun the cometbegins to melt.

• The melted ice and dust becomes the comet’s tail.

• The tail gets pushedaway from the Sun from the pressure.

Where a Comet Comes From

• Kuiper Belt– A region beyond Pluto’s orbit– Probably contains 40,000 to 70,000 objects with

diameters of more than 100 km. • 100 Kilometers = 62.1371192 Miles

• Oort Cloud– Surrounds the solar system about 15 trillion km

from the Sun

Hailey’s Comet

• Orbits past Earth every 76 years.

– The last close pass was in 1986, and the next is due in 2061.

Earth

What Is Earth Like?

• Special because it is the only planet in the solar system that supports life.

Layers of Earth• Inner Core• Outer Core• Mantle• Crust – What we live on

• Hydrosphere– Thin layer of water

• Atmosphere– Thin layer of gases

Earth’s Atmosphere

• Protects us from small debris from space.

• Made up of:– Nitrogen (78%)– Oxygen (21%)– Other gases (1%)

Atmospheric Layers• Troposphere– Nearest Earth’s surface– Where weather occurs

• Stratosphere– Ozone helps absorb harmful ultraviolet radiation from the Sun

• Mesosphere

• Thermosphere

Magnetic Field• The area that surrounds a magnet.– Invisible lines of force that run from one pole to the other.

• Earth has one as if there were a giant bar magnet buried inside it.

Van Allen radiation belt• Discovered by the American satellite, Explorer 1

• Acts like a shield, protecting us from particles from the Sun.