• The student will recognize the major common characteristics of all planets and compare/contrast the properties of inner and outer planets.

• The student will distinguish among the following objects of the solar system-sun, planets, moons, asteroids, comets-and identify Earth’s position in it.

• The student will recognize that a galaxy consists of gas, dust, and many stars, including any objects orbiting the stars and identify our home Galaxy as the Milky Way

• A SOLAR SYSTEM is made up of a star and all the planets and other objects that revolve around that star. Our solar system consists of the Sun and the 8 planets that revolve around it. It is a small part of a much larger system called the Milky Way Galaxy.

• Our Sun is the largest object in our solar system and is considered to be a star. It is the closest star to Earth – a yellow dwarf star – smaller than most stars

• The outer temperature of the Sun can reach 6,000 degrees Celsius!

• 109 Earths would fit across the Sun.• Did you know the Sun has been active for 4.6

billion years?

The Sun

Our Moon• Called Luna• No air, water or life on the moon• Made of rocks and craters (big holes in the surface of the moon formed when meteorites crashed into it millions of years ago)• Gravity is not as strong as the gravity on Earth (you can jump high on the moon)• Nearest neighbor in space (about 238,000 miles from us)• Moon does not actually make its own light, it reflects the light from the Sun • Orbits the Earth – it takes 28 days to orbit around the Earth one time, this is called a lunar cycle

Phases of the Moon

• A PLANET is a body that revolves around a star. We have 8 planets in our solar system that revolve around the sun.

• Mercury • Venus • Earth • Mars • Jupiter • Saturn • Uranus • Neptune

Located between Mars and Jupiter, The asteroid belt separates the Inner Planets from the Outer Planets.Planets closest to the Sun are smaller

and mostly solid (formed from heavy, rocky materials).

Planets farthest from the Sun are larger and formed mainly of gases.

Inner Planets

• Mercury– Closest to the sun

– Very weak atmosphere, which means little air

– No water

– Many deep scars on its surface from huge meteorites

– Days are very hot and nights are very cold

– Has no moons

– Scientists do not think there can be life here

• Venus– Second from the sun

– brightest planet

– Has a layer of thick, poisonous, yellowish clouds made of sulfuric acid (no life possible)

– Both days and nights are very hot and windy

– No water

– No moons

– Often called Earth’s “twin planet” because it is almost the same size as Earth

Inner Planets• Earth

– Third planet from sun– Has everything living things

need: sunlight, water, and certain gases

– Has an atmosphere made up mostly of nitrogen and oxygen

– has a magnetic field that comes from the core of the Earth and pylls everything in. This keeps you from floating away – gravity

– Spins or rotates around sun like other planets

– Has night and day– Has one moon that orbits it,

called Luna– Supports many life forms

• Mars – Fourth planet from the sun– Nights and days much like Earth– Has clouds, fog, volcanoes, and

canyons, sand dunes, boulders and rocks, craters

– Very cold temperatures and severe dust storms

– Scientists believe there used to be large, deep lakes on mars – no liquid water there now (there are frozen polar ice caps)

– Often called the “Red Planet” because its soil is red

– Has two tiny moons– Possibility that there might be life– ROVERS mission in 2003

Outer Planets• Jupiter

– Fifth planet from the sun– Largest planet (more than 1000

Earths could fit inside it)– Gas giant, almost entirely made

of gas– Large red spot – believed to be a

guge gas storm that has lasted for hundreds of years. It is 3 times the size of our planet Earth.

– Fast moving clouds surround Jupiter to form the wide bands called “zones” and the narrow bands called “belts”

– Has rings, active volcanoes, lightning bolts

– At least 17 moons

• Saturn– Sixth planet from the sun– Also a gas giant– Best know for it’s brilliant rings

made up of chunks of rock, ice and dust (believed to form when objects get too close and gravity pulls them into orbit around the planet)

– Has a striped appearance like Jupiter – these are swirling clouds

– Has at least 22 moons – one is Titan, the largest moon in the solar system

Outer Planets

• Neptune– Eighth planet from the sun– Gas giant– Very cold planet – Very far away, it takes 12

years to get there– Blue-green planet, like

Uranus– Very stormy– Has 8 moons – one moon is

Titan, which has many geysers (springs that shoot up super-heated vapors (gases) constantly)

• Uranus– Seventh planet from the sun– A gas giant that looks blue-green

because of the methane gas in the atmosphere.

– Faint gray rings around it – At least 15 moons– Rotates differently than the other

planets – it spins as though it is lying on its side (scientists thought another planet’s gravity might be pulling it to spin like that. They looked for another planet that might be doing this and found Neptune)

• Thousands of rocky lumps that form a circle around the Sun in a big band between Mars and Jupiter.

• One of the biggest asteroids, Ceres, is about 620 miles across. Others are as small as a grain of sand.

• More than 3,200 asteroids have been identified so far.

• Leftover rocks from the time when the planets were first formed

ASTEROIDS

• A small orbiting body made of dust, ice, and frozen gases (like dirty ice-balls)

• Only a few miles in diameter• A comet’s tail always points

from the Sun, regardless of the direction the comet is moving.

• Comets travel around the Sun in long, elliptical paths.

• Sometimes a comet is drawn toward the Sun and it comes hurtling down through the solar system. As it travels, it melts and leaves behind a tail of gas.

Comets

• Start off as lumps of rock in the asteroid belt between Mars and Jupiter. The rocks break out of the belt and travel on their own.

• Once they start flying through space, beyond the asteroid belt, they are called meteors. • They may be grains of dust from comets, chunks of rocks, or even bits of shattered asteroids. • Most meteoroids burn up in the atmosphere. If they strike Earth’s surface, they are called meteorites. • Its a streak of light caused by a small chunk of matter called meteoroid that enters Earth’s

atmosphere and is heated by friction with air.• A meteor shower occurs when hundreds of meteors move through the sky in a short period of time.

Meteors

Stars• There are trillions of stars in the universe• You can probably see about 3000 on a clear night• Stars are classified by their color, temperatures, sizes, and brightness• Have life cycles

1-Begins as a cloud of gas and dust called a Nebula2-Cloud moves around and picks up more and more gas and dust – like a snowball rolling down a hill and getting bigger and bigger and gets really big and hot3-eventually runs out of gas and burns out – the burnt out star will blow up, shrink or go cold. This whole cycle can take billions of years to happen

*Blue Stars- bigger than yellow stars, called blue giantsthey are very bright and very hot. When they die they larger and larger and then explode into a …*Supernova- so bright that they can be seen from very far awaySuper giant stars – largest that can be seen with bare eyes is calledBetelgeuse. It is 700 times bigger than the Sun.

Galaxy• Galaxies are huge collections of stars, dust and

gas. They usually contain several million to over a trillion stars and can range in size from a few thousand to several hundred thousand light-years across. There are hundreds of billions of galaxies in the universe. Galaxies come in many different sizes, shapes and brightness and, like stars, are found alone, in pairs, or in larger groups called clusters. Galaxies are divided into three basic types: spirals, ellipticals and irregulars.

CAST OF GALAXIES…THE 3 MAIN TYPES OF GALAXIES.

Spiral galaxies get their name from the shape of their disks. In a spiral galaxy, the stars, gas and dust are gathered in spiral arms that spread outward from the galaxy's center. Spiral galaxys are divided into three main types depending on how tightly wound their spiral arms are: Sa, Sb and Sc. Spiral galaxies have a lot of gas, dust and newly forming stars. Since they have a lot of hot, young stars, they are often among the brightest galaxies in the universe. About 20% of all galaxies are spirals. We live in a spiral galaxy called the Milky Way.

Elliptical galaxies are shaped like ellipses (stretched circles). They are divided into eight types: E0-E7 depending on how elliptical they are. E0 ellipticals are nearly circular, while E7s are very stretched out. Elliptical galaxies are made up of mostly old stars, and do not have much gas and dust. There is very little new star formation in these galaxies. Elliptical galaxies also come in many sizes. The largest galaxies we see are elliptical, but, elliptical galaxies can also be small. About 60% of all galaxies are elliptical.

Irregular galaxies have no particular shape. They are among the smallest galaxies and are full of gas and dust. Having a lot of gas and dust means that these galaxies have a lot of star formation going on within them. This can make them very bright. The Large and Small Magellan Clouds are examples of irregular galaxies. They are two small galaxies which orbit around our own Milky Way galaxy. About 20% of all galaxies are irregulars.

THE MILKY WAY…Our home in the stars…

The Milky Way is the galaxy in which we live. It is a spiral shaped galaxy that contains about 200 billion stars, including our Sun. It is about 100,000 light-years across and about 10,000 light-years thick.

If you are at a place which has a very dark night sky, you can sometimes see the Milky Way as a thick band of stars in the sky. We

live near the edge of the Milky Way.

It takes the sun 200 million years to make one rotation around the center!

A constellation is a group of stars visible within a particular region of the night sky. Some were named after animals and some mythological characters. Some constellations were named after some scientific instruments. Constellations can be viewed after sunset and before sunrise. Also, as the earth turns you can see different constellations.

Let’s Review

• Which of the following is the correct order of the inner planets, from innermost to outermost?– A. Jupiter, Mars, Earth, Saturn– B. Mercury, Venus, Earth, Mars– C. Mercury, Mars, Earth, Venus– D. Mars, Earth, Venus, Jupiter

Let’s Review

• The Sun is at the center of our Solar System. Which of the following correctly describes out sun?– A. star– B. planet– C. galaxy– D. meteorite

Let’s Review

• The Earth – A. orbits between Mars and Jupiter.– B. rotates around the moon.– C. is the third planet from the Sun.– D. is the center of the Solar System.

Let’s Review

• Our Galaxy is called the– A. Stream of Milk– B. Stream of Stars– C. Galaxy Quest– D. Milky Way

Let’s Review

• Jill and her father observed the Big and Little Dippers at the same time each evening for four weeks, using a tree in her yard as a reference point. They made sketches of their observations and noticed that the constellations changed their positions relative to the tree in her yard over this time period. What caused this apparent change of position?

• A. The Earth was revolving around the sun.• B. The constellations were revolving through phases of

the night sky.• C. The Earth was rotating on its axis.• D. The constellations were rotating around a point in the

night sky.