WARM UP

What two things determine the strength of an object’s gravitational force?

PLANETARY FORMATION AND MOONS!

How do scientists theorize the formation of planets? What are moons?

Review

Gravity is the force that pulls objects toward each other.

The strength of gravitational force depends on the MASS of the object DISTANCE between the objects

MASS

100,000 kg

100kg

DISTANCE

STRONG GRAVITATIONAL FORCE

WEAK GRAVITATIONAL FORCE

The Formation of a Planet

1. A star supernovas (explodes) and sends off HUGE amounts of dust and rock.

2. The gravitational force of a large rock pulls in smaller rocks and dust.

3. The new planet continues to “grow” until no more rocks and dust are left around it.

http://www.youtube.com/watch?v=_mcC8kFacrk&feature=related

SOLAR SYSTEMS

What is a solar system and what are the characteristics of ours?

Review

Outer space contains planets, stars, natural satellites (moons) asteroids, meteoroids, and comets.

Solar Systems

A solar system is a collection of celestial bodies (planets, moons, asteroids, etc) orbiting a star.

Our Solar System

Our solar system contains 1 star (the Sun) 8 planets 240 known moons Comets (giant balls of ice) Asteroids (flying space rocks) Meteoroids (small asteroids)

The Formation of a Planet

Gravity holds a planet together in a spherical (round) shape.

Types of Planets

Types of Planets

The two types of planets are Terrestrial Planets –

Rocky planets with a solid surface (examples: Earth, Mars, Mercury)

Gas Giants – Giant planets made mostly of gas (examples: Jupiter, Saturn, Uranus)

Terrestrial Planets

The 4 planets closest to the Sun are terrestrial planets (aka: rocky planets or inner planets). Mercury Venus Earth Mars

Asteroid Belt

The asteroid belt is a huge area containing asteroids and meteoroids located between the inner and outer planets.

Gas Giants

The 4 planets furthest from the Sun are Gas Giants (aka: Jovian/outer planets). Jupiter Saturn Uranus Neptune

The Kuiper Belt

The area surrounding our solar system composed almost entirely of comets.

Planetary Satellites

A planetary satellite is a natural object that orbits (revolves around) a planet due to gravity. Also known as a MOON.

Planets don’t always have moons.

Some planets have many moons.

Phases of the Moon

The phases of the moon occur because of the moon’s revolution around Earth.

The lit portion of the moon that we see changes depending on the position of the moon around Earth.

Planets

Memory tip: “My Very Excellent Mother Just Served Us Nachos.”

EXIT SLIP

What are the two different types of planets?

What is the major difference between the inner and outer planets in our solar system.