Live from McDonald Observatory
Teacher Edition for grades 9 – 12
Introduction
The videoconference will introduce students to McDonald Observatory, telescopes, and the sun. The worksheets are designed to help the student discuss important concepts. Students should be directed to not fill in their sheets until prompted.
Visiting the Otto Struve Telescope
During the videoconference, the students will receive a behind-the-scenes tour of the 2.1-m Otto Struve Telescope. The facilitator will point out and describe the parts of a telescope and how they work by using the Law of Reflection, which the students can visualize by use of the worksheet. We will also discuss the instruments used to study celestial objects, such as cameras that take images, rather than a person looking in an eyepiece. Note that the Otto Struve telescope uses several different mirrors to send the focused light to different physical locations where different instruments may be used. One commonly used location is directly behind the primary mirror – this means that a hole was cut into the center of the primary mirror. Telescopes are housed in buildings, usually domes, which open to the sky to allow the light from astronomical objects into the telescope. The building protects the telescope from weather damage.
What figure(s) illustrate the Law of Reflection?
Note that the rays with arrows illustrate beams of light. It is recommended that an activity on reflection be completed prior to the videoconference. Students should understand that the angle of incidence equals the angle of reflection for any mirror. Figure B is a wrong answer and most students will recognize that. Many students will answer Figure A, which is correct for a flat mirror; however, Figure C is also correct. Astronomers often use parabolic mirrors for telescopes because all the reflected rays will come to the same point. The equation for a parabola is y2=ax.
In each of these cases, the rays are being reflected at an angle (measured from the normal of the surface) equal to the incident angle. After the discussion in the videoconference, students should make the connection that the curved mirror and is like the mirrors used in telescopes.
References and Extensions:
For a history of the telescope, visit the NASA website at:
For hands-on activities involving the Law of Reflection:
Mirror, Mirror: <
Delta, Delta, Delta: <
For more information about the Otto Struve Telescope:
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Live from McDonald Observatory
Teacher Edition for grades 9 – 12
Investigating our star the Sun
Prior to the videoconference, students should have filled in the pre-assessment sheet. The drawings and words that they use will help you gauge their pre-conceptions as well as prepare them for encountering new information about the sun.
Following the tour of the telescope, the facilitator will provide commentary while showing images of the sun in white light and light that has passed through an H-alpha filter. The facilitator will perform demonstrations to make important links between physical concepts and the sun.
In the box, students should draw a feature they can see on the sun. Their drawing should be like a zoom-in of a part of the sun, i.e. there should not be a full disk. (In the pre-assessment, it is likely that they drew a full disk image.)
When matter becomes a plasma, does it make a chemical or physical change?
Correct Answer: B, physical
If students answer “chemical,” it should be explained that plasma is just like other phases of matter, such as solid, liquid, and gas. The matter is the same substance, just in a different form.
In the Sun, energy moves in the following ways: (A) Convection; (B) Conduction; (C) Radiation.
Correct Answers: A and C
Most students should answer “radiation” knowing that the sun emits light. In the videoconference discussion, convective layers in the Sun will be discussed, and so students should retain this in answering the question and also answer “convection.” Because conduction involves heat transfer from a solid touching something, and the Sun is made of plasma, not solid, students should understand there is no conduction in the Sun. If students answer this wrongly, it should mostly result simply from not thinking the situation through. Once it is pointed out, they should easily follow the logic leading to this conclusion.
References and Extensions:
Plasma:
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Many website discuss convection, conduction, and radiation. Here are some samples:
An H-alpha filter allows only radiation near the Balmer line, H-alpha, to pass to the detector. It is the transition in the standard Bohr model of the hydrogen atom from n=3 to n=2. This transition occurs at 656.3 nanometers wavelength. Using this filter allows the astronomer to observe the chromospheric layer of the sun.
Live from McDonald Observatory
Teacher Edition for grades 9 – 12
Equipment and Hardware used in solar observations
This page gives students a better understanding of the equipment involved in acquiring the images they are seeing of the Sun during the videoconference. The purpose of this page is to allow students to make the connection between science and technology. Technology provides improved means for scientists to acquire a better understanding of the universe.
There are three telescopes here:
- The large one is used for close-up views of portions of the sun. It has an H-alpha filter. The entire aperture of this telescope is not used for solar viewing. Although it is difficult to see in this image, there is a cap on the end of the C-14 that has a small hole cut so as to limit the total amount of light that is collected by the telescope and camera.
- One of the 76-mm telescopes provides a white-light full-disk image. Because the sun is so bright, a neutral density filter is used to cut-down the amount of sunlight reaching the camera.
- The other 76-mm telescope provides a full-disk image through an H-alpha filter.
Students may be surprised to learn that the computer is similar to those that they may use at home or school. Although astronomers use special software on their computers, often a standard home-quality computer is sufficient for the data management of many projects. (Note: astronomers who work on making mathematic models of astronomical phenomena or who have extremely large data bases do require special computers.)
References and Extensions:
Live from McDonald Observatory
Teacher Edition for grades 9 – 12
Sunspot Challenge
In this activity, students consider the data as plotted, plot additional data points, analyze the data, and predict future trends.
The students should be able to plot the data fairly accurately. When analyzing the trend, there may be variable responses such as:
- noting the changing trend, i.e. “It goes up and down.”
- noticing specific details, such as
- the dip in the first peak, the point for 1996 is lowest,
- the point for 1989 is highest,
- the second peak isn't as high, the dip in the first peak
- noting the periodicity of the curve
It is important that students note this periodicity in order to predict the future trend. When they predict data for 2006-2010, their lowest point should be at 2006 then turn upward in the following years. By 2010, their data should be nearing a new peak. Students who do not notice the periodicity before plotting their predictions may have plots with data steadily declining, or staying at a constant value.
As the first astronomical user of a telescope, Galileo was also one of the first astronomers to observe sunspots (although records of Chinese astronomers observing sunspots with the unaided eye go back to about 1000 BC, they were not done systematically.) The records from Galileo's time onward illustrate the 11-year cycle that is due to regular changes in the magnetic field of the sun. Sunspots can be used to calculate the sun's rotation rate (which is different for the equator and poles, since the equator rotates faster). An active sun (many sunspots, flares, prominences) means more violent space weather on Earth (e.g., more disruptions of communication and more aurora as charged particles stream from the sun and are trapped in Earth's magnetic field.)
References and Extensions:
The diagram at the right was taken from
There are many references to sunspots and solar phenomena
For general pictures and information about observing the Sun, visit the Solar & Heliospheric Observatory (SOHO) website at:
To check out daily photos of the Sun and track sunspots through SOHO: