 ## Astronomy activities for Elementary students

Astronomy / September 30, 2016

1. Begin by discussing the vastness of the universe. For example, tell students that light travels at the unimaginably fast speed of 300 million meters per second, and yet light takes years to travel to us from the stars and takes thousands or evenmillionsof years to travel the depths of space between galaxies. When we’re dealing with those kinds of distances, it’s no wonder that we often think of them as being beyond our grasp. One way to put these distances into perspective is to think of them as multiples of smaller-scale distances. By putting these quantities in the context of a well-understood frame of reference, they begin to have more meaning.
2. Help students grasp our place in the enormous universe by reviewing your school’s “galactic address”—beginning with its street address and ending with its place in the universe. Discuss the different units of measurement that are used to describe distances in each part of the galactic address. Give students examples for each step, or have them use reference materials to provide their own examples. Review any unfamiliar units of measurement, such as light-years and astronomical units. By thinking about their location on a small scale first and then moving out to a much larger scale, students begin to get a sense of how distance is measured at each scale.
 Place Units of measurement Example Street address Feet, meters (within a house) A room might be 10 × 14 feet. City Miles, fractions of miles You might drive ½ mile to the grocery store; a town might be about 10 miles wide. State Tens to hundreds of miles The distance from Austin to San Antonio is a little more than 50 miles; Texas is about 600 miles across. United States Hundreds to thousands of miles The distance from New York to Los Angeles is 3, 000 miles. Earth Tens of thousands of miles. Earth’s circumference is 25, 000 miles. Solar System Millions to billions of miles, or astronomical units (AU). (An AU is the average distance from Earth to the sun, or 93 million miles.) Neptune is 30 AU, or 2.79 billion miles, from the sun. Milky Way Galaxy Hundreds of thousands of light-years. (A light-year is the distance that light travels in one year, or about 6 trillion miles.) The Milky Way is about 100, 000 light-years across. Local Group (a cluster of about 20 galaxies, including the Milky Way) Millions of light-years The Andromeda galaxy is about 2.2 million light-years away from our Milky Way galaxy. Supercluster (a group of clusters) Hundreds of millions of light-years The Virgo supercluster of galaxies is about 150 million light-years across. Universe Billions of light-years The farthest known galaxy (the edge of the observable universe) is 13 billion light-years away.
3. Explain that one way to put the enormous sizes and distances of space into perspective is to compare them to smaller scales that are easier to grasp. In this activity, students will convert distances and sizes in space to smaller units. To begin, distribute the Classroom Activity Sheet: Understanding Sizes and Distances in the Universe, and have students work in pairs to answer the questions.
4. To help students understand how to solve these problems, you may wish to do the following problem together as a class:

Problem: Using a scale in which a quarter represents Earth, what would the distance from Earth to the moon be?

Solution: Three pieces of information are needed in order to determine this scale distance to the moon: the diameter of the quarter, Earth’s diameter, and the actual distance from Earth to the moon. Measuring the quarter reveals that it has a diameter of 1 inch. Earth’s diameter is about 8, 000 miles. The actual distance from Earth to the moon is an average of 240, 000 miles, although this distance can vary with the moon’s orbit around Earth. For these calculations, though, the average can be used. Now that we have these three pieces of information, we can find the fourth piece (the scale distance) by setting up the following ratio:

This is equivalent to the statement “The diameter of a quarter is to Earth’s diameter as our scale distance is to the actual average Earth-moon distance.”

Substituting what we know shows us that:

Remember that it’s important to keep track of the units. If Earth’s diameter had been given in kilometers, it would be incorrect to use 240, 000 miles for the Earth-moon distance. We would need to convert that distance to kilometers, too. Because both diameters are given in miles, they cancel each other and can be crossed out of the equation. In this problem, we should expect our result to be in inches, the same unit as the quarter’s diameter. By multiplying both sides of the equation by 240, 000 miles to isolate, we find that

d = (240, 000 miles) × (1 inch/8, 000 miles) = 30 inches

So, at this scale, the distance between Earth and the moon would be 30 inches.

5. Before students start working on the problems, it may be useful to go over scientific notation, which is a helpful way to deal with large numbers. Use the following examples to illustrate the powers of 10:
• 1 can be written as 100(because anything to the power zero is 1).
• 10 can be written as 101(because anything to the first power is itself).
• 100 can be written as 102(because 10 multiplied by itself, or 10 × 10, equals 100).
• 1, 000 can be written as 103(because 10 multiplied three times, or 10 × 10 × 10, equals 1, 000).
Explain that we can use these powers of 10 to represent decimal places, too:
• 3.4 can be written as 3.4 × 100.
• 99.1 can be written as 9.9 × 101.
• 4, 526 can be written as 4.526 × 103.
Review the properties of exponents to make scientific notation even more useful:
• When multiplying two numbers with exponents, if the base numbers are the same, just add the exponents. For example, 105× 103= 108.
• When dividing two numbers with exponents, if the base numbers are the same, subtract the exponents. For example, 104/102= 102.
6. Have each pair of students solve the problems listed below, which also appear on the Classroom Activity Sheet: Understanding Sizes and Distances in the Universe. Also included for students are constants that provide helpful information to be used in scaling. Students must figure out which information is needed to solve each problem. Students can work with partners to solve the problems, but each student should fill out his or her own sheet. All the questions from the Classroom Activity Sheet and the answers are listed below. Questions on the Classroom Activity Sheet: Understanding Sizes and Distances in the Universe

If Earth were the size of a penny

• how large would the sun be?(81 inches, or 6.7 feet, in diameter)
• how far away would the sun be?(8718.75 inches, 726.5 feet, 242 yards)
If the sun were the size of a basketball
• how far away would Neptune be from the sun?(3237 feet, or 0.6 miles)
• how far away would the nearest star, Proxima Centauri, be from the sun?(5, 538 miles)
• how far would it be to the center of the Milky Way? (36, 538, 218 miles)
• About how many trips to the moon does this distance equal?(152)
If the Milky Way were the size of a football field
• how far away would the Andromeda galaxy be?(6, 600 feet, or 1.25 miles)
• how far would it be to the farthest known galaxy?(39 million feet, or 7, 386 miles)

• A penny is about ¾ inch in diameter.
• Earth is 8, 000 miles across.
• The sun has a diameter of 861, 000 miles.
• One mile equals 5, 280 feet.
• The average distance from Earth to the sun is 93 million miles.
• A basketball is roughly 12 inches in diameter.
• Neptune is 30 AU from the sun, or 2.79 billion miles.
• One light-year is 6 trillion miles.
• The nearest star, Proxima Centauri, is 4.2 light-years away.
• The sun’s distance from the center of the Milky Way is about 30, 000 light-years.
• A football field is 100 yards (300 feet) long.
• The Milky Way is about 100, 000 light-years across.
• The distance to the Andromeda galaxy is 2.2 × 106light-years.
• The farthest known galaxy is 13 billion light-years away.

Source: www.discoveryeducation.com