THE SOLAR SYSTEM

Scientists construct ideas to explain the solar system. The geocentric model was based solely on unaided observations. This model was challenged and eventually replaced by the heliocentric model.

Today, thanks to advanced technology such as space probes and radio and optical telescopes we know that the solar system is made up of the Sun, eight planets, moons, asteroids, comets and meteors.

All of these celestial bodies revolve around the Sun in their own orbit. The solar system we know extends billions of kilometers in all directions from the Sun.

THE PLANETS The planets are grouped into 2 categories based on a few similar features. The inner planets, Mercury, Venus, Earth and Mars, are called the terrestrial planets because they all have rocky composition. The outer planets, Jupiter, Saturn, Uranus and Neptune, are similar because they are all composed of gas. Pluto was in its own category because of its unique orbit and tiny size but it is now no longer considered a planet.

ASTEROIDS, COMETS AND METEORS

Asteroids, comets, meteors and meteorites are part of our solar system. Asteroids are “minor planets” located between Mars and Jupiter. They range in size from 1 meter to hundreds of kilometers. Asteroids are irregular shaped bodies of carbonaceous and silicate rock. Scientists have identified 5000 asteroids but they speculate that millions of asteroids exist.

Comets are solar objects made of dust and ice. They can easily be detected with a telescope and sometimes can be seen with an unaided eye. The model that scientists have designed for a comet resembles a “dirty snowball”. Millions of comets orbit the Sun. When a comet gets bumped from its orbit, by gravitational pull, it moves toward the Sun and it begins to melt and evaporate which forms comet tails that can be thousand of kilometers long.

Meteors and meteorites are dust and rock fragments Meteors and meteorites are dust and rock fragments. When a meteor heats up it will burn. The burning of a meteor is commonly referred to as a “shooting star”, however, it is not a star at all. Meteorites are large meteors that strike the earth. These meteorites can be dangerous but most often they provide material for study.

TASKS Do #1-4 pg. 431 Page. 442 # 2, 7 Complete the P. 446-447 using Planet Data Cards pg. 448-451 Page 456 # 4,5 Chapter Review page 458 # 5 (use Planet Data Cards pg. 448-451