Volume 1 - Winter 2007

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The following model lesson was modified for STARLAB from the Lowell Observatory Web site which offers a wide variety of elementary, middle and high school level activities. These activities can be found at http://www.lowell.edu/Public/Starlab/StarlabSupp.html

How Many Stars Are In The Sky? A Model Lesson for STARLAB

Suggested Grade Level

Elementary/Middle/High

Objectives

  • Using math and a paper towel tube, estimate the total number of visible stars to the unaided eye.
  • Use averaging to increase accuracy of star estimations.

Materials

Procedures

  • Have the students make a prediction of how many stars the think are in the visible sky. Write this prediction down on the Star Count worksheet. While looking through a paper towel tube into the STARLAB starfield, count how many stars that can be seen in the following directions:
    • Elementary students: north, south, east, west, and up.
    • Middle/High students: choose any location on the horizon, then make a count from 10, 30, 45, 70, and 90 degrees above the horizon. Caution the students to keep the tube as still as possible when counting. The rule for counting might include any star you see in the tube including those that are faintly visible.
  • Multiply each answer by 104. One hundred-four represents the number of paper towel tube observations it would take to cover the visible sky. This answer is your estimated number of stars in the sky. Why does each direction have a different answer?
  • Average the answers as shown on your star count data sheet. Follow the directions on the worksheet for calculation. This is your grand total of stars in the sky. Repeat this procedure a second time if time permits. When all students have their grand totals, average the class totals.
  • Have the students compare their predictions to the class average. Note: The number of stars projected by the Basic STARLAB projector and Starfield Cylinder is approximately 1500 stars at one time. The FiberArc Projector has a brighter light source thus will produce slightly brighter star images allowing students may see more stars. The Digital STARLAB software can assign limiting magnitudes of stars thus allowing the sky to be saturated with stars or minimized to match local sky conditions. Keep in mind that the numbers of stars visible to your students will vary with dark adaptation and vision.

Extension

Conduct this activity in the real sky on different nights and different sky conditions (i.e., new moon, full moon, in the city, in the country)

More Ideas for Teaching Mathematics in STARLAB Using the Earth Cylinder

Measurement of Distance

  • The scale of distance in the standard dome is approximately 1” = 42 mi. or 67 km
  • The scale of distance in the giant dome is approximately 1” – 28 mi. or 45 km
  • Statute Mile, Kilometer, Geographic Mile, Standard Nautical Mile

Parallels of Latitude

  • These are the Small Circles parallel to the Equator, and joining places of the same latitude. The circumference of these Parallels decreases as we move away from the Equator towards the Poles.
  • With the Equator as zero, latitude is measured in degrees, minutes, and seconds of arc north or south of the Equator.

Circumference of Parallels of Latitude

  • The distance around a parallel of latitude varies as the Cosine of the Angle of Latitude (i.e. Distance on Parallel = Distance on Equator x Cosine Latitude). This formula is used to calculate the distance between two places on the same Latitude (i.e. difference of Longitude in Minutes of Arc x Cosine latitude = Distance in Nautical Miles).

The Angle of Longitude

  • Meridians (longitude) converge and meet at the poles. Longitude refers to the angle formed at the poles between the Greenwich Meridian, and the Meridian that passes through a given location. Longitude is measured in degrees, minutes, and seconds of arc from 0 to 180 degrees, either East or West of Greenwich.

Time Zones

  • Earth is divided into 24 time zones each covering 15 degrees of longitude. Time on the Greenwich Meridian is used as Standard Time, and is known as Greenwich Mean Time or GMT.
  • Time changes by one hour for every 15 degrees of Longitude East of Greenwich, up to 12 hours ahead of GMT at the 180th meridian, or by one hour for every 15 degrees West of Greenwich up to 12 hours behind GMT at the 180th Meridian.

International Date Line

  • At the 180th Meridian the Western side is 12 hours ahead of GMT, while on the Eastern side we are 12 hours behind. When the International Date Line is crossed, we either gain or lose a full day.
We have pdf versions of STARLAB News back issues from Winter 1995 to Fall 1999. Issues prior to XII, Winter 1995 are not available as a pdf. Please contact LTI directly for availability.

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