Name: Lab Day and Time: Partner's Name: The Scale of Things Lab Activity 1 Goals The purpose of this lab is to help you gain some perspective on some astronomical distances and times by creating a couple of simple models of size, distance and time. You will work with a partner to provide one measurement for each of three models. Other pairs of students in the class will provide other measurements. The result will be a scaled drawing or model of different star sizes, our Solar System, and the age of the universe. In the process, you should gain some insight to the scale of some things as well as practice some of your math and proportional reasoning skills. (There is some math help on the last page of this Lab.) 2 The Size of Stars The nearest star to Earth, the Sun, is one of billions of stars in our galaxy, one of billions of billions of stars in the universe. Other than being our "own" star, it's not particularly remarkable in any way as stars go. It's only average in size. Maybe even on the small size. Stars range from smaller to significantly larger than our Sun. In this part of the lab, we're going to compare the radii of some common stars. The lab instructor has a pool from which you will (randomly) draw out one of the following stars: Betelgeuse, Rigel, Beta Lyrae, Deneb, Antares, Arcturus, Aldebaran, Capella, Beta Pegasi, Sirius, Altair, Hadar, u' Scorpii A, Procyon A. You and your partner will create a scaled drawing of your chosen star. Depending on weather (and other factors), this drawing will either be on large paper with marker, on the floor of the lab room with a dry erase white board marker, or in the parking lot or on the street in chalk. Look up your star in Wikipedia. Find your star's radius. If the radius is not listed in solar radii, convert. A measurement in "solar radii" means that it's a radius compared to our Sun's radius. For example, if a star has a radius of 3.8 Rooter, that star is 3.8 times larger (in radius or diameter) than our Sun. Your chosen star: Size (solar radii): Size at which the Sun is drawn: Size at which you need to draw your star: In the manner determined by your TA, draw an outline (circle) that represents your star. Label your sketch clearly with the star's name and size (in solar radii). When all groups are finished, list the sketched stars here in order from largest to smallest: Lab instructor check point PH104: Descriptive Astronomy Page 1 of 53 A Scale lIodel of the Solar System In the second part of this lab. you and your partnerm'll help create a model of the solar system. The lab instructor has a pool from which you and your partner \"ill (randomly) select one solar system object You and your partner still do two things: each to a different scale. 1] You will create a scaled and cut-out circle that represents the correctly scaled size ofyour chosen object. This still be done at one scale. 2) 1fou will then place your object in the appropriate position in the classMilt solar system model. This twill be done at a diEferent scale. Depending on weather {and other factors]. this model \"ill either be down the hallway outside of the lab room [room 206) or will be dottnthe sidewalk outside of the building. Look up your chosen object [in your textbook or on the internet.) You need two pieces of information; the size of your object and its average orbital size. [Its semimajor axis will out) You will want the orbital size measured in AL". Your chosen planet object; Planet'object diameter in km Orbit Size (AU) For the object size scale. we still make the Sun 130 inches {10 feet} tall. Calculate the scaled size of your object. (You'll need the diameter ofthe Sun to complete this calculation.) Scaled Planet object diameter in inches: Draw your planet object to the proper scale. A compass may be used to draw a smooth circle; there are compasses available in the lab room. Scissors are also ayailahle. Cut out your planet object. For the orbital size scale: we 13.111 make the length of the hallway the distance om the Sun to the outer edge of the Kuiper Belt about ii AL". Length of hallway in meters [from TA): Size of one AL" in our halluay (sidewalk) model: Distance from the Sun you still use to position your object {in meters): Attach your scaled circle and label to a ring stand Position your object in the correct place in the model Solar System in the hallway. .-'t long tape measure is available. Take a stroll through the completed model and look at the dismbtnion of the planets. Where are they more \"bunched up"? More spread out? Mostly. where are the smallest planets located? The largest? PH104: Descriptive Astronomy Page 2 of 5 Why were two different scales used for this solar system model? (Hint: To fit to the scale of the hallway, the Sun would be less than 1 inch high.) Lab instructor check point 4 The Cosmic Calendar In the "Cosmos" television series, Carl Sagan introduced the idea of the Cosmic Calendar. He suggested that we imagine the entire history of the universe scaled to fit within one calendar year, with the Big Bang at midnight on the morning of January 1, and us, today, at the other end of the year at midnight at the end of the last day of the year, December 31. We round off the age of the universe to 14 billion years; that is, the Big Bang occurred 14 billion years ago. Other historical events are then placed on the (scaled) calendar date when they take place. The lab instructor has a pool from which you and your partner will (randomly) select an event in history. Look it up (internet probably) and find how long ago your event occurred. There will likely be some variability in times dates but find a best estimate. (Note that we are believing in science and astronomy here and using scientifically accepted values, not religious values which might suggest most everything on our list occurred less than 10,000 years ago.) Your chosen event: How long ago did this event occur. Date (and time if appropriate) where this event occurs on the Cosmic Calendar: Write your event and date on an index card and place it on the Calendar in the lab room in its correct position. When all groups are finished, list four events from different dates and the date on which they occurred. Event Years Ago Calendar Date 1. 2. 3. 4. PH104: Descriptive Astronomy Page 3 of 5How many years are represented by each day on the Cosmic Calendar? How many years are represented by each second on the Cosmic Calendar? All of recorded human history, every person that we have ever heard of, all of this is within the last 5000 years (or so.) What date and time is that on the Cosmic Calendar? Lab instructor check point PH104: Descriptive Astronomy Page 4 of 55 If you need some help with the math... Everything you need to calculate in this lab can be done with mathematical ratios. (Although, the calendar events can get slightly more complicated.) For example, to find the scaled size of some object relative to the scaled size of the Sun, set up the following ratio: actual size of the object in km X inches actual size of the Sun in km scaled size of the Sun in inches You will look up the actual sizes of the object and the Sun and the scaled size of the Sun is given to you in the lab activity. You therefore have 3 of the values in the above equation and will solve for "x". The calendar events are found from similar ratios. For example: years ago the event happened x days years ago the Big Bang Occurred 365 days If some event occurred 10 billion years ago, you would set up as follows: 10 billion years ago X 14 billion years ago 365 days 10 X= ------ X 365 days = 261 days. 14 So, this event occurred 261 days before the present moment (midnight, December 31.) You'll have to count backwards then to find the date on the Cosmic Calendar. If the time your event occurred is so short that it is less than one day ago, you'll need to set up a similar ratio but use the number of minutes or seconds in the year (instead of number of days.) 6 A Couple of Last Things For our hallway Solar System model, a distance of one light-year would be approximately 75 miles. The nearest star to us (that isn't our Sun) would be about 300 miles (4 ly x 75 miles/ly) away! Imagine a sphere of space, 300 miles in radius, surrounding our model, all the known planets tiny or even invisible specs, the Sun less than 1 inch tall, and all the rest of that 300 mile-radius sphere filled with practically nothing! That's our nearest neighborhood! Make sure you're satisfactorily checked off for your lab by the TA. PH104: Descriptive Astronomy Page 5 of 5