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Geology 8 Learning Activity 4: “Solar System Scale and Number of Planets in the Universe” Part 1: Scale of the Solar System Introduction: The solar system is BIG. The sun is BIG. The planets are big too, but the sun is huge. The distances between the planets are huge too! Today we are going to be making 2 scales of the solar system: The first is a scale of relative sizes of each of the main solar system bodies. The second is how far apart each is from one another. Table 1 below gives the diameters of each of the worlds in centimeters. Table 2 gives the distance of the objects from the sun, in meters. Note for the Sun in table 2, this is the diameter of the sun in meters. For the moon, this is the distance from the Earth to the moon. Table 1 OBJECT Diameter (cm) Diameter (cm) (1/10,000,000,000) Diameter (cm) (1/5,000,000,000) Sun 139,140,000,000 13.9 cm 27.8 cm Mercury 487,900,000 Venus 1,210,400,000 Earth 1,275,600,000 Moon 347,500,000 Mars 679,200,000 Jupiter 14,298,400,000 Saturn 12,053,600,000 Uranus 5,111,800,000 Neptune 4,952,800,000 Pluto 237,000,000 Table 2 OBJECT Distance (m) Distance (m) (1/100,000,000,000) Distance (ft) Sun* 1,391,400,000 0.01 m 0.03 ft Mercury 57,900,000,000 0.5 m 1.6 ft Venus 108,200,000,000 Earth 149,600,000,000 Moon** 384,400,000 Mars 227,900,000,000 Jupiter 778,600,000,000 Saturn 1,433,500,000,000 Uranus 2,872,500,000,000 Neptune 4,495,100,000,000 Pluto 5,906,400,000,000 Materials: · A compass (the kind you draw a circle with) · A ruler · A tape measure · Chalk if you have it, or just rocks will do as well. Your task 1. Complete the charts on the first page. a. On the first chart (Table 1), convert the diameters of the object to 1 ten billionth the scale. In other words, we are shrinking the solar system objects down to 1/10,000,000,000 their actual size! I’ve done the size of the sun for you. Another way to think about this is, if the sun were shrunk down have a diameter of 13.9 cm, how big would the rest of the planets be? b. For the first empty column (1/10,000,000,000) take the second column (Diameter (cm) and divide it by 10,000,000,000. Or just move the decimal place over 10 times. Write that number in the 3rd column. Hint, yes, these should be small numbers! c. In the last column, we are now going to convert it to “just” 1/5,000,000,000 their actual size. This will help make them large enough to draw on a single piece of paper. To do this, just multiply the column you just made (the 3rd column) by 2 and place that value in the empty box. d. Now, using the values in the last column (1/5,000,000,000) and a compass, draw circles to represent the size of each of the objects. Note, some of them will be very difficult to do! Be sure to label each one. Put them all together on the next page of this handout. Hint, it will be easier to just draw ½ of the sun, not the full circle! In other words, just draw it so it looks like ½ a pizza. Note, you can do this using a compass, or a ruler, or just in Word. You can draw a circle by using the “insert” tool and click on shapes, and find the circle icon. Click on that circle, then click on the page, a circle should appear. Now, if you click on the circle you just drew you should see something that says “format shape.” Click on that, and at the far right side, you can change the size of the circle by typing in a number. Hint, click on the box that is between the 2 measurements, that will “lock” the shape so that the up-down and left-right diameters stay equal to each other. You can convert these to inches, OR just type in the the number you need and write “cm” after and word will convert it for you. Draw sun and planets here. Hint, they will mostly be VERY VERY SMALL! 2. Now lets see how big the solar system would be if the sun was just 1/100,000,000,000 its actual size. Note this will be 20 times smaller than what you just drew! We are shrinking the solar system down even more! a. In Table 2, convert the actual distances to a 1/100,000,000,000 scale size. To do this, just divide each value by 100,000,000,000 or just move the decimal over 11 times. I’ve done the first 2 for you. b. Now, use google to convert these values to feet and write those values in the last column of table 2. c. Draw a circle that is the scaled size of the sun. Note this is the value from table 2. This is how big the sun would be on our solar system. Draw it in the box below. It’ll fit! d. Now pace out how far each planet would be if the sun were the size of the image you just drew. If you want bring along a friend or family member. Maintain all socially distant requirements. Hint, this is best if you can do this outside on a straight bit of sidewalk. Place a rock, or draw a dot for the location of the sun. Then, using the tape measure, go out from the sun and mark the distance to each plant. For example, Mercury will be just about 1.5 feet from the sun. Neptune will be much farther away! Note, if you don’t have a tape measure or a safe means to do this, that is fine. But it helps to actually SEE the distances you calculated in table 2! If you are able to do this outside, take a picture of it and include it here! Note, a photo is not required. Questions for thought 1) How many Earth’s across is the sun? 2) How many Earth’s across is Jupiter? 3) Which would be wider across, Jupiter, or all the other planets lined up side by side? 4) Which planet is farthest apart from any other planet (note, Pluto is NOT a planet) 5) If Neptune were on one side of the sun, and Uranus was on the other, how far apart would they be (in km)? Assuming you wanted to send a radio signal this distance, how long (in hours) would it take to get from one to the other (assume it travels at 300,000 km/sec). Part 2: How many planets are there in the universe? Introduction: Caution, math ahead. Astronomy is very math focused. But we don’t need to be afraid of it! Today we will be doing some simple “back of the envelope” calculations. All you need is your brain and a calculator. We are going to make some estimates for how many planets there are in our galaxy and in our universe. We can then guess how many of those planets may have life! This exercise is simplified version of something called the “Drake equation” which set out to determine how many civilizations there could be in the universe. That equation looks like this: N = R*Fp*Ne*Fl*fi*fc*L where: N = Number of civilizations who we could detect radio waves from R = Rate of formation of stars suitable for the development of intelligent life Fp= The fraction of those stars that have planets Ne= The number of planets per solar system that are suitable for life Fl= The fraction of planets that actually produce life Fl= The fraction of life producing planets that actually produce intelligent life fc= The fraction of planets that produce intelligent life that develop technology that emit detectable signals L = The length of time until those signals reach earth * means multiply (times) This equation is just an estimate and there could be other variables too! Assumptions: The Milky Way is an average galaxy The Milky Way contains 200 billion stars (200,000,000,000) The universe contains 1 trillion galaxies (1,000,000,000,000) (*note, this is probably low) Assume every galaxy contains as many stars as the Milky way. Exercise 1) What percentage of stars do you think have planets? It can be between 100% and just a little more than 0. Less than 1% is an option! Note, this is entirely up to you! There is no wrong answer. 2) Take the percentage and convert that to decimals. For example, if you said 50% of stars have planets, you would write 0.50 below. 3) On average, how many planets would be around each star? Note, our star has 8, but you can put any number you want. You can even put down less than 1. For example, if you think one out of every 10 stars has just 1 planet (on average), you can put down 0.1 (1/10). 4) Based on your estimations, how many planets are in the Milky Way? Take 200,000,000,000, multiply it by the number you wrote for question 2 (it should be less than 1!). Now take that number and multiply it by the number from question 3. Write that number below. 5) Based on your estimations, how many planets are in the universe? Take 1,000,000,000,000 and multiple it by the number you wrote in question 4. Write that number below. Hint, this is probably still a REALLY big number. 6) Now you can play with your initial estimates. What happens if you change one of your numbers by a lot? For example, say you started off with 99% of the stars having planets, what happens if you say 1% have planets, or less! Does the number of planets in our galaxy change all that much? 7) Are there aliens somewhere? Lets see how many worlds may have life on them. NOTE, there is no scientific evidence for aliens visiting Earth. However, there could be other life somewhere! To find out how many places may have life we need another variable. How many planets could have life? Write down how many planets you think have life. For example, our solar system has 8 planets, one has life. So