Astronomy: The Scale of the Solar System
Comparing distances, sizes, and travel times in space
Astronomy: The Scale of the Solar System
Comparing distances, sizes, and travel times in space
Astronomy - Grade 6-8
- 1
One astronomical unit, or AU, is the average distance from Earth to the Sun. About how many kilometers are in 1 AU?
This distance is based on Earth's average distance from the Sun.
One astronomical unit is about 150 million kilometers. - 2
Mars is about 1.5 AU from the Sun. If 1 AU is about 150 million kilometers, about how far is Mars from the Sun in kilometers?
Mars is about 225 million kilometers from the Sun because 1.5 times 150 million equals 225 million. - 3
Jupiter is about 5.2 AU from the Sun. If 1 AU is about 150 million kilometers, about how far is Jupiter from the Sun in kilometers?
Multiply the distance in AU by 150 million kilometers.
Jupiter is about 780 million kilometers from the Sun because 5.2 times 150 million equals 780 million. - 4
A scale model uses 1 AU = 10 centimeters. On this model, Earth is 10 centimeters from the Sun. Neptune is about 30 AU from the Sun. How far from the Sun should Neptune be placed in the model?
Convert centimeters to meters after multiplying.
Neptune should be placed 300 centimeters, or 3 meters, from the Sun because 30 times 10 centimeters equals 300 centimeters. - 5
In a classroom model, 1 AU is represented by 2 meters. How far from the Sun should Saturn be placed if Saturn is about 9.5 AU from the Sun?
Saturn should be placed 19 meters from the Sun because 9.5 times 2 meters equals 19 meters. - 6
The Sun's diameter is about 1,390,000 kilometers. Earth's diameter is about 12,742 kilometers. About how many times wider is the Sun than Earth?
Divide the Sun's diameter by Earth's diameter.
The Sun is about 109 times wider than Earth because 1,390,000 divided by 12,742 is about 109. - 7
Light from the Sun takes about 8.3 minutes to reach Earth. Jupiter is about 5.2 times farther from the Sun than Earth is. About how long does sunlight take to reach Jupiter?
Multiply 8.3 minutes by 5.2.
Sunlight takes about 43 minutes to reach Jupiter because 8.3 times 5.2 is about 43.2. - 8
Neptune is about 30 AU from the Sun. If light takes about 8.3 minutes to travel 1 AU, about how many minutes does sunlight take to reach Neptune?
Sunlight takes about 249 minutes to reach Neptune because 30 times 8.3 equals 249. - 9
Convert your answer from the previous problem to hours and minutes. Use 60 minutes = 1 hour.
Divide 249 by 60 and keep the remainder as minutes.
Two hundred forty-nine minutes is 4 hours and 9 minutes because 240 minutes is 4 hours and 9 minutes remain. - 10
Put these planets in order from closest to the Sun to farthest from the Sun: Mars, Mercury, Earth, Venus.
The correct order is Mercury, Venus, Earth, and Mars. - 11
The asteroid belt is mostly between about 2.2 AU and 3.2 AU from the Sun. Mars is about 1.5 AU from the Sun, and Jupiter is about 5.2 AU from the Sun. Between which two planets is the asteroid belt located?
Compare 2.2 AU and 3.2 AU with the distances of Mars and Jupiter.
The asteroid belt is located between Mars and Jupiter because its distance range is greater than Mars's distance and less than Jupiter's distance. - 12
The Kuiper Belt begins near Neptune's orbit at about 30 AU and extends to about 50 AU from the Sun. How wide is this region in AU?
The Kuiper Belt region described is about 20 AU wide because 50 AU minus 30 AU equals 20 AU. - 13
A student draws the planets equally spaced on a poster. Explain why this is not an accurate scale model of the solar system.
Think about the difference between Earth's 1 AU distance and Neptune's 30 AU distance.
This is not accurate because the distances between planets are not equal. The outer planets are much farther apart than the inner planets. - 14
In a scale model, Earth is 1 meter from the Sun. On the same scale, Uranus is 19 AU from the Sun. How far from the Sun is Uranus in the model?
Uranus is 19 meters from the Sun in the model because 1 AU is represented by 1 meter. - 15
A model uses a marble 1.3 centimeters wide to represent Earth. On this scale, the Moon would be about 38 centimeters away from Earth. What does this show about the space between Earth and the Moon compared with their sizes?
Compare a 1.3 centimeter Earth model with a 38 centimeter Earth-Moon distance.
This shows that even nearby objects in space are separated by large distances compared with their sizes. The Moon would be many Earth diameters away from the marble Earth.