Planets  Universe Origin  Solar System  Big bang??  Explosion of H mass 14 billion years ago.  Moved outward began condensing into galaxies  Protoplanet Hypothesis??  Solar system, planets and 61 natural satellites  5 planets seen w/o telescope (Mercury, Mars, Venus, Jupiter and Saturn)

C. Observing the Solar System 1. Geocentric- earth at center Ptolemy- Greek astronomer developed the idea

2. Heliocentric- sun at center Copernicus- Polish astronomer developed idea Galileo supported idea

 Inner Planets  Outer Planets  Terrestrial Planets  Mercury, Venus, Earth and Mars.  Jovian, gaseous or Jupiter like planets  Jupiter, Saturn, Uranus and Neptune

Neptune Jupiter Uranus Mars Mercury Pluto Earth Saturn Venus Jovian- Jupiter like. Outer planets Inner planets: Terrestrial planets

One rotation takes 59 days. One year is 88 days. It has no moon or rings. Mercury is the closest planet to the sun. It looks a lot like our moon. Click here to learn about Mercury.

One rotation takes 243 days. One year is days. It has no moon or rings. Venus is the second planet from the sun. It is as dry as a desert and hotter than an oven.. Click here to learn more about Venus.

One rotation takes 24 hours. One year is 365 1/4 days. It has 1 moon and no rings. It is the third planet from the sun. Earth is mostly covered with water.

One rotation takes 24.5 hours. One year is 687 days. It has 2 moons and no rings. It is the fourth planet from the sun and the last of the inner planets. Mars looks red because of rusty iron in its soil and red dust in its air.

One rotation takes 9.8 hours. One year is 12 earth years. It has at least 16 moons and 2 rings. It is the fifth planet from the sun and the first gas planet. It has a great red spot of swirling gas.

One rotation takes 10.7 hours. One year is 29.5 Earth years. It has at least 17 moons and many rings.It has at least 17 moons and many rings. Saturn is the sixth planet from the sun and the second gas planet.Saturn is the sixth planet from the sun and the second gas planet. Saturn’s rings are made of ice, rock, and dust.Saturn’s rings are made of ice, rock, and dust.

One rotation takes 17 hours. One year is 84 earth years. It has at least 15 moons and 10 rings. Uranus is the seventh planet from the sun and the third gas planet. Uranus seems to rotate on its side.

One rotation takes 16 hours. One year is 165 earth years. It has 8 moons and 4 rings. It is the eighth planet from the sun and the last gas planet. Neptune is blue-green.

Is it a planet? One rotation takes 6 days. One year is 248 earth years. It has 1 moon and no rings. It is the ninth, and last planet from the sun, but every 248 years Neptune orbits farther than Pluto. Charon is Pluto’s moon.

Galaxies  Galaxies  A system of clustered stars that slowly spin in space.  Telescopes show that space contains at least several billion galaxies.  Our solar system is in the Milky Way Galaxy.  The Milky Way belongs to a small cluster of 17 galaxies called the LOCAL GROUP.

 Types of Galaxies  There are three main types of galaxies.  Spiral – 1. have a central lens shaped bright nucleus made of millions of stars. 2. Arms that trail behind the galaxy as it rotates.  Elliptical – 1. nearly spherical to lens shaped. 2. Their brightness patterns show that most of their stars are close to the center. 3. They have no arms and almost no gas and dust clouds

 Irregular Galaxies 1. Smaller, fainter, and less common than the others. 2. Their stars are spread unevenly. With the information that has been provided identify the following galaxies…..

A. B. C. Classify these 3 galaxies. Spiral Elliptical Irregular