The EUVE Orbit

by Del Spicer and Leslie Dietiker

1995 The Regents of the University of California

Here's a Description of Our Lesson Plan


This lesson will cover at least two days, but it will work best with three full days. Here is a short synopsis of the daily plans:


This day is an introduction to orbits and the EUVE satellite mission. On-line resources on the EUVE NASA satellite mission can be found in the CEA Home Page. Be sure to cover the following topics:


Have students spread around your classroom in small groups with supplies as specified in this lesson's Preparation.)

Obtaining Your Own Data from the EUVE Satellite:

One of the innovative aspects of this lesson plan is that the students will be able to use an interactive feature of this lesson plan to obtain position data from the EUVE satellite.

By using this interface you will access information from the EUVE satellite in the form of its position above the Earth (called the EUVE ephemeris) and in the sky against the background stars (called the EUVE orbital position).

The program computes the position of the EUVE Satellite in both terrestrial longitude and latitude (as seen from above the Earth) and against the sky (as seen from the center of the Earth) in Right Ascension and Declination. Astronomers use Right Ascension and Declination to find their way around the sky in a similar fashion that we find out way around a map of the Earth using longitude and latitude. To use the interactive program, you may specify

The interactive tool allows students to obtain the following information as a function of time, displayed in columns:

Once the students obtain this file of data by using the interactive tool, they will then be able to use the data file produced to plot the position of the EUVE satellite projected on the Earth using this "world map." Students can also plot the position of the EUVE satellite against the background stars using this "sky map."

Using the Interactive Tool:

You may want to let your students experiment with what would be reasonable values for these parameters that they'll have to provide when using this interactive tool. For example, a student may enter his or her birthay for the current year as the starting time, in the format specified in the interactive tool (e.g. 09/02/94:00:00:00 for Sep. 2, 1994). Then, the student may choose a time step or interval of a few minutes to a few months, plot the data for 50 or 100 time steps, and figure out if his or her parameter choices are reasonable. Since the orbital period of the EUVE satellite is approximately 93 minutes, (that is, it takes EUVE 93 minutes to go once around the Earth), a reasonable choice of time interval and time unit for plotting the EUVE orbit might be every 5 to 10 minutes, plotted for 50 or 100 time steps. Let your students experiment and discover the EUVE orbital period by plotting data at several different time intervals.

Have each student in each group access the EUVE satellite's position data using the Interactive Tool. The students can plot the latitude and longitude data pairs from the output file on their world map, using the Earth's equator as the x-axis of their graph. If done properly, this graph will result in a sine curve. The same plotting procedure can be used for marking the position of the EUVE satellite in the sky projected against the background stars.

Once the students are making progress plotting the EUVE position above the Earth onto their individual copies of the world map, they can also plot their points on the big color copy of the world map that is provided for the whole classroom.

It will also be interesting for the students to compare their plots for the same time intervals that they have made on the world map against their plots on the sky map. They should find that due to the Earth's rotation, the sine curve that they plot on the world map will be compressed with respect to the sine curve they plot on the sky map.

Comparing Results With Computer-Generated Plots From This Lesson Plan:

At the end of this discovery period, the groups could write a brief report summarizing their observations and predictions for the orbit of the EUVE. Students can view a map of the world with the already-plotted real-time position of the EUVE satellite by using this lesson plan as well. To obtain a computer-generated plot of the EUVE orbit and real-time position, click here. Student groups can then compare their plotted data with the calculated position and shape of the orbit as shown by the computer-plotted map, discussing any discrepancies.


This day is best to allow groups to finish their work from the previous day. The world map in front of the class should be finished and discussed. Have the students reflect on their previous activity and discuss properties of orbits. Students should be ready to talk about periods and amplitude of sine curves, even if they are unaware of the sine function.

It might be fun to have the students figure out which countries and bodies of water the EUVE flies over. This could lead to a discussion about predicting when the EUVE satellite will be over a specific geographical location.

Worksheets and Handouts:

On day one, we feel it would be helpful for the students to receive a glossary of terms important to this project which can be given to them as homework assignments in preparation for this lesson plan. Examples of such terms are:

  1. Equator
  2. Latitude
  3. Longitude
  4. Right Ascension
  5. Declination
  6. Electromagnetic Spectrum
  7. Extreme Ultraviolet Light
  8. Orbit
  9. Orbital Period
  10. Northern and Southern Hemispheres
  11. Earth's Axis

The only other necessary handout is a copy of a world map. Try to find one with the equator exactly in the center of the map.


The students are responsible for revising their data and graphing on graph paper before the third day, so that they will be available for class discussion of orbital periods and geography.

The glossary of terms can be assigned ahead of time to have the students practice researching information.


Optional segment for Advanced math courses involving trigonometry. These students can calculate period and amplitude of this sine/cosine function as well as creating an equation using the format:

y = b cos (x - d)

For more information about this lesson plan:




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