Our Solar System
By Cindy Grigg
-------------------------------------------------------------------------------1 Our solar system has many parts. The solar system is made of our sun and
everything that orbits around it. This includes the planets and their moons. It also
includes asteroids, meteors, and comets. These things are held in orbit by the sun's
gravity.
2 There used to be nine planets. Pluto used to be called a planet, too. But scientists
have decided that Pluto isn't really a planet at all. Now our solar system has eight
planets. They are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
They are listed in order by their distance from the sun.
3 Some of our planets have moons, or satellites, that orbit the planet. Earth has one
moon. Jupiter and several other planets have many moons. Mercury and Venus don't
have any moons.
4 Planets move two ways. They move around the sun in almost circular orbits. The
other way they move is that they rotate. This means they spin around on an imaginary
axis like a top. It takes Earth one year to complete its orbit around the sun, or make
one revolution around the sun. It takes Earth one day to rotate on its axis.
5 Four of the planets are larger than Earth. They are Jupiter, Saturn, Uranus, and
Neptune. Three of the planets are smaller than Earth. They are Venus, Mars, and
Mercury. Venus is only a little smaller than Earth.
6 Between Mars and Jupiter lies an asteroid belt. This is an area containing many
asteroids. Asteroids are large chunks of rock and metal. Pieces of asteroids that break
off are called meteors. Comets orbit the sun, too. Comets are big chunks of ice, gas,
and dust. Sometimes they are called "dirty snowballs."
7 Scientists who study our solar system use big telescopes. There have been several
space probes sent to take pictures of most of the planets. There is an International
Space Station, called the ISS, where astronauts live and work in space for several
months at a time. It seems the more people study space, the more they want to learn.
Copyright © 2007 edHelper
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Name _____________________________
Date ___________________
Our Solar System
1. What is in the solar system?
The sun and everything that orbits around it
Planets and their moons
Asteroids and comets
All of the above
2. What keeps the planets in orbit?
The moon's gravity
The planets' gravity
The sun's gravity
3. How many planets are in the solar system?
Eight
Seven
Five
Six
4. Which planet is almost the same size as Earth?
Jupiter
Venus
Mars
Mercury
5. ______ are called dirty snowballs.
--------------------------------------------------------------------------------------------------------------------------------------------------------------6. How do we know about the other planets?
Telescopes, space probes, and the International Space Station
We are only guessing.
We have traveled to the other planets.
7. Another word for "moon" is ______.
Satellite
International Space Station
Space shuttle
Planet
8. Planets move in how many ways?
They don't move at all.
They move in one way.
They move in three different ways.
They move in two ways.
Our Solar System - Answer Key
1 All of the above
2 The sun's gravity
3 Eight
4 Venus
5 Comets
6 Telescopes, space probes, and the International Space Station
7 Satellite
8 They move in two ways.
The Milky Way Galaxy
By Cindy Grigg
-------------------------------------------------------------------------------1 Our solar system is a small part of a galaxy. Galaxy is the name given to a large
system of stars, planets, gas, and dust. Gravity holds a galaxy together. Our galaxy is
called the Milky Way galaxy. It has an estimated 200 billion other stars besides our
own sun. At least some of these other stars have planets orbiting around them.
2 As a galaxy, the Milky Way is actually a giant. Its diameter is about 100,000 light
years. A light year is the distance that light travels in one year. A light year is about
9.5 trillion kilometres or about 6 trillion miles.
3 The Milky Way is a barred spiral galaxy with four arms. This means it is a spiral
shape with a bar of bright stars in the centre running across the middle. There are four
arms that look like they trail off the bar. Our solar system is located in a smaller spiral
arm called the Local Group or Orion Arm.
4 Our solar system is about 4.6 billion years old. Our sun is a young star. Scientists
think the Milky Way galaxy may be about 14 billion years old.
1. What is a galaxy?
The universe
The solar system
A large system of stars held together by gravity
2. We live in the ______.
Orion galaxy
The Local galaxy
The Milky Way galaxy
Andromeda galaxy
3. Our sun is the only star to have planets orbiting it.
False
True
4. The Milky Way is a small galaxy.
False
True
5. How big is the Milky Way galaxy?
6 trillion miles across
9.5 trillion kilometres across
100,000 light years across
6. The Milky Way is described as ______.
A spiral galaxy
An irregular galaxy
A barred spiral galaxy
7. Our solar system is in the middle of the galaxy.
False
True
8. How old is the Milky Way galaxy?
4.6 billion years old
14 billion years old
10 billion years old
The Milky Way Galaxy - Answer Key
1
2
3
4
5
6
7
8
A large system of stars held together by gravity
The Milky Way galaxy
False
False
100,000 light years across
A barred spiral galaxy
False
14 billion years old