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A lab exercise for students to understand measuring tools and techniques used in astronomy to determine distances to celestial objects. Students will explore everyday measuring tools, learn about parallax and stellar magnitudes, and calculate distances to stars like betelgeuse and deneb. The exercise also covers the sizes and distances of earth, the sun, and other objects in the solar system and beyond.
Typology: Lab Reports
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Your Name______Ava Piper________
After completing this exercise you should -
Science is all about measuring. One of the most important parts of doing astronomy is measuring distances, angles, and luminosity of celestial objects. In Astronomy the distances are huge and unimaginable. You might ask yourself the question “How can you gather information about an object that is so far away that you cannot reach it? For example, how do we know if a star is far away, but very bright, or close to Earth and relatively dim? Before we start with exploring astronomical distances you will investigate how you measure things in everyday life, and what tools you can use.
1. List at least 10 tools that you use for measuring things in your everyday life. Clock, thermometer, measuring cup, yardstick, ruler, bathroom scale, kitchen scale, speedometer, tape measurer, phone/Aitness tracker 2. If you were going to measure the area of your room what kind of measuring tools might you use? I would use a tape measurer or a yardstick to measure my room.
Parallax as explained in the pre-lab activity, is an interesting way of measuring the distance of an object by how much it appears to move when viewed against a much more distant background from one location, then another ( the distance between the locations is called the baseline ).
2. Print a paper meter stick and tape it to your arm so that your chin can rest on the “0” mark. With your other hand hold a pencil or pen at the 50 cm mark. Then shut Airst one eye, then the other and observe how the pencil moves against objects in the background. Describe what happens The pencil moves more towards the right when my right eye is closed and towards the left when my left eye is closed.
3. Move the pencil closer, to the 25 cm mark. What happens to the motion of the pencil now when you Airst close one eye and then the other? Can you quantify the difference? Is the motion apparently twice as much as it was before? Five times as much? Write your answers below. The motion of the pencil was more signiAicant when I moved it to 25 cm. I’d say the motion of _the pencil is twice as much as it was when it was at 50 cm.
We will begin by shrinking the Earth to a two – inch diameter circle, then scaling other objects close to earth to see how they compare.
Earth has a diameter of approximately 12756 km. We will use the metric system measurements for all astronomical objects today. Since one inch is 2.54 cm, it would be more consistent with the metric system to think of this a 5 cm universe. However, since the United States still doesn’t use the metric standard, most of us are used to thinking in terms of inches and feet and have a better idea of what an inch is (about the length of your thumb from top joint to tip) than what a cm is. Now do the math. In this realm 2 inches = 12756 km and the Moon is 3475 km in diameter, so how many inches in diameter would it be in our two inch Earth/Moon system? or, putting in the numbers
In other words the moon’s diameter is about .54 inches, or about ¼ the diameter of the Earth. Do the same process to calculate the distance the Moon is from Earth. In this case x is the distance of Moon from Earth in the model, but you will now need to use the fact that the Moon is about 384403 km away from Earth on average when measuring from the centers of Earth and Moon. Now we have: Doing the math we get x = 2 (384403/12756) or 60 inches. Since 1 foot = 12 inches that is about 5 feet away. Other sizes and distances In this model, where the Earth is 2 inches across, the Sun is about 18 feet in diameter (imagine a round, glowing mini-van!) and is 1800 feet, or about 6 football Uields away from Earth
The next stage of this exercise is to shrink the Sun down to a 2 inch diameter. The Sun is approximate 1400000 km in diameter. Write this number in scientiUic notation.
1. The absolute magnitude, M, is deAined as the apparent magnitude a star would have if it were placed 10 parsecs from the Sun. But wouldn’t it be more correct to measure this distance from the Earth? Does it make a difference whether we measure this distance from the Sun or from the Earth? _The answer is yes given how far distant the two places are from one another.