1. The Planets
Chapter 7 Lesson 3
Page 340

2. What makes up the solar system?
A solar system is made of a star and the objects that orbit around it
A planet is a large object that orbits a star
A moon is a natural object that orbits a planet
All but two planets in our solar system have one or more moons
From nearest to furthest from the sun- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune (My Very Educated Mother Just Served Us Nachos!)
Different types of small objects are present in space: comets, asteroids, and meteors.

3. What makes up the solar system? (continued)
A comet is a mixture of frozen gases, ice, dust, and rock that moves in an elliptical orbit around the Sun.
An asteroid is a rock that revolves around the Sun
Meteoroids are small objects in space. If they enter into Earth’s atmosphere they are called meteors.

4. What are the inner planets?
The inner planets are:
Mercury, Venus, Earth, and Mars
Closer to the sun
They share common characteristics:
They all have surfaces made of rock
They are known as the terrestrial planets
These planets have few or no moons
None of them have rings

5. What are the inner planets? (Continued)
Mercury is the closest planet to the sun, and its surface looks a lot like the Moon’s surface
Venus has a surface that shows evidence of violent volcanic activity.
Earth is the largest inner planet and is the only planet in the solar system known to support life
Mars is known as the red planet because it has a reddish surface color

6. What are the outer planets?
The outer planets are
Jupiter, Saturn, Uranus, and Neptune
The four planets beyond the asteroid belt
They have some similarities
Made mostly of gas
They have a metallic core and a thick atmosphere
They are much larger than the inner planets
All have rings and many moons
A day on an outer planet is very short; they spin very rapidly on their axes

7. What are the outer planets? (Continued)
Jupiter is distinct because of The Great Red Spot which is a storm that has been blowing for more than 400 years.
Saturn is known for its large, bright rings. The rings are made of pieces of ice and rock
Uranus has a distinctive blue-green color due to the methane in the planet’s upper atmosphere
Neptune has the strongest winds of any planet and appears blue.

8. Dwarf Planets
Pluto was once known as the ninth planet. In 2006, the International Astronomical Union officially reclassified Pluto as a dwarf planet

9. How do the moons compare?
Different planets have different numbers and sizes of moons
The inner planets have fewer moons than the outer planets
Mercury and Venus have no moons; Jupiter and Saturn have at least 60 moons
Moons are also called satellites
A satellite is an object in space that circles around another object
Humans have created artificial satellites that include weather and communication satellites

10. How do we explore the solar system?
Exploration of other worlds started in 1959 when a Soviet rocket carrying scientific instruments landed on the moon.
Space Probes are vehicles carrying instruments that are sent to explore objects in space

11. Quick Facts
The 4 inner planets are made of rock, and few moons
The 4 outer planets are made of gas, with many moons
The closer to the sun, the shorter the orbit
The further from the sun, the longer the orbit
The outer planets spin faster on their axes, therefore, they have shorter days