Baker Lab 2 - Telescopes

Baker Lab 2 - Telescopes

Katelynn and Aubrey

Abstract

Using a telescope, we can make a wider range of observations of the night sky than we can with the unaided eye. Telescopes allow us to see more objects in the night sky, as well as see more detail in objects than we can see without the telescope. Learning to set up a telescope is the first step toward using the device to make observations the universe around us.

Introduction

This lab report is an introduction to working with telescopes. The primary focuses of the lab are to learn to set up a telescope and learn to use it. Once the telescope is mounted on its stand, it needs to be focused in order to observe objects.

Procedure

1. Form a group to work with. Make sure there are only as many groups as there are telescopes.

2. Set up the telescope using instructor’s directions.

3. Find a bright object, such as a star or the moon, in the sky to look at. Align the telescope up with the object then use the finder-scope to help aid in finding the object in the telescope.

4. Look through the eyepiece of the telescope and find the object. Focus the telescope on the object and note where the object is in the finder-scope in order to make finding additional objects easier.

5. Watch the object move across your field of view in the eyepiece. Record data.

6. Turn tracking on the telescope on. Pick an object to observe, like part of the Milky Way or the Andromeda Galaxy.

7. Use a star finding app or chart to locate your chosen item in the sky.

8. Answer the lab questions about the objects you have located in the sky.

9. Disassemble your telescope.

Results and Discussion

Only numbers from the assigned lab that contained questions are included in the R&D.

4. The knobs on the telescopes need to be focused in order to change the distances between the lenses inside the telescope. The focal points of the lenses must line up in order to see a clear image.

5. We positioned our telescope so that Jupiter was at the edge of our field of view. We then measured the amount of time taken for Jupiter to drift across our field of view and leave sight, noting that it took approximately two minutes. Jupiter, and other observable objects, appear to drift across the night sky because of Earth’s rotation. In other words, they’re not actually moving, but Earth’s axial rotation causes our view of the distant universe to continually change.

6. We did not use tracking because we did not have time this lab night.

8. a. When looking at Jupiter through the telescope, we could see two moons and faint stripes on the planet. Minor details were visible, much like they are in the example below:

This image is extremely similar to what we observed through our telescope, although perhaps a little more detail is visible here. This image presents what we say better than our crude, 5-second sketch done in the dark.

b. Through the telescope, two of Jupiter’s stripes are very apparent, and they are aligned with the tidal forces of the two observed moons. It is easy to identify it as Jupiter with this telescope. Although the color of the planet is not obvious through the telescope, the texture is.

c. Two large moons are also clearly visible. They lined up with the planet’s stripes and tilt, as expected. The two we saw were two of Jupiter’s four largest: Io, Europa, Ganymede, and/or Callisto. Their surfaces are simply bright points of light surrounding the planet. We cannot make further observations about their surface using the given telescope. However, considering their relative orbital periods and distances from Jupiter, the two observed moons are most likely Io and Europa. The Galilean moons and their orbital periods around Jupiter are modeled in the following image:

The rings around Jupiter are too faint to see with the telescope used.

d. Our object of choice was not the moon.

e. Our object was one of the brightest in the night sky on this night. It appeared to be an incredibly bright star. While with the eye, Jupiter appeared to be a tiny point of light, perhaps 1mm or less in diameter, it was magnified to perhaps 1cm through our telescope. Therefore, we estimate that Jupiter was magnified by an approximate factor of 10.

f. Although we did not look at a star, we could see more objects in general in the sky when using the telescope, compared to using the unaided eye. Jupiter’s moons are invisible to the naked eye, however they are bright when using a telescope.

g. We did not observe a star or cluster of stars.

h. When covering the open end of the telescope with a piece of paper, the light in the eyepiece gradually becomes dimmer. The rate at which light dims seems to be somewhat exponential. The brightness appears unchanged until a large portion of the lens is covered, and then fades quickly as you cover more of the lens. You cannot see the outline of the paper because we observing and gathering light that is travelling from an enormous distance, so the paper serves to block some of the light gathered and is much too close to the telescope to be able to see.

The reason you can still see the object in the sky when half the light is blocked is because the telescope is gathering light and magnifying it into a smaller image. From our eyes’ point of view, the image is still crisp so long as there is enough light to form the image after the lenses focus the light. When the light is blocked, there are fewer light waves to focus into a small, magnified image. As this happens, the small image becomes dimmer.

i. Our object did not change in brightness.

Jupiter

            Jupiter, the largest planet in our solar system and one of the brightest objects in the night sky, was first observed in detail by Galileo in 1610 with the invention of the telescope. In this way, Galileo was able to discover 4 of Jupiter’s 67 known moons: Io, Europa, Ganymede, and Callisto. The discovery of objects orbiting something other than Earth became a major argument for Copernicus’ heliocentric model of the solar system.

            Jupiter is a gaseous planet composed of about 90% hydrogen and 10% helium, with trace amounts of methane, ammonia, water, and rocky material, and has a density of 1.33 g/cm³ – slightly greater than the density of water. Jupiter is believed to consist of a relatively small, dense core, surrounded by a layer of liquid metallic hydrogen and helium, and an outer layer of mostly hydrogen in molecular form. Observable on Jupiter’s surface are high-speed winds, grouped in bands of like-color and moving in adjacent directions. The directions of movement are parallel with the tidal forces created by Jupiter’s moons. Interestingly, Jupiter produces a greater amount of energy than it receives from the Sun. Due to Jupiter’s large mass, its core is subject to a large gravitational force, and is therefore compressed and heated, causing the radiation of thermal energy. Unlike the Sun and other stars, nuclear fusion of Hydrogen does not occur in the core of Jupiter; it does not possess enough mass to reach the required temperature (~10,000,000 K). In fact, the minimum mass required to begin hydrogen fusion is about 0.08 M_Sun, and Jupiter’s mass is only about 0.00095 M_Sun, or 1.898 x 10²⁷ kg.

Conclusion

            This lab allowed students to gain valuable skill in assembling telescopes and using them to observe objects in the night sky. Parts of this lab were pretty difficult, including locating Jupiter in the field of view of our telescope, and then keeping it there as Jupiter continually drifted out of view. However, accomplishing all of this, as well as being able to observe Jupiter in detail, was extremely rewarding.