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Measuring the Universe

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Main Topics & Concepts
What Do Astronomers Measure?
How Do They Measure Things Far Away?
This topic applies to California State standard 4c in 8th grade Earth Science and standards 1d and 2a.
Science Probe Text
Science Probe I 14.5, The Brightness of Stars is about the concepts of relative and absolute magnitude and modeling how they can be measured. 

Activity Access Description
Science Probe I:
Activity 14E

Indirect Measurement Using Triangulation
book Students measure the distance to a distant object from a locally measured baseline,  using geometry.
Science Probe I:
Activity 14G

The Magnitudes of Stars
book Part I asks students to compare stars' brightness in naked-eye observations.  Part II is a laboratory on the rate at which brightness decreases with distance from a light source. Knowing the distance to the star is the key to absolute magnitude.


Activities & Lessons
Activity Access Description
Desktop Stars, Part I
Center for Particle Astrophysics
web Part 1 of this  3-part activity  teaches students about the inverse square law of radiation intensity, using a simple laboratory setup with a light bulb, meter stick, and a simple photometer (or even your hand).  A teacher's guide and student worksheets are provided.
Activity J-2. Parallax -- How Far Is It?
Universe at Your Fingertips ASP*
book Students use the method of parallax to determine the distances to various objects inside and outside the classroom.  A possible alternative to Science Probe I activity 14E
The Relationship between Angular Size and Actual Size

NASA/Imagine the Universe
web Students are introduced the the idea of angular size and given two exercises to calculate angular size of everyday and celestial objects.  The relation between angular size and distance to the object  is explained.
Activity J-3. Hello Out There!
Universe at Your Fingertips ASP*
book An activity to help students understand the idea of light travel time as a measure of distance. Should be done after building a scale model of the solar system, such as Science Probe I activity 13B.
G-6. Count Your Lucky Stars:  Sampling in Astronomy
More Universe at Your Fingertips ASP* 
book Student practice using a sampling window on everyday objects, then to estimate the number of stars in the sky visible to the unaided eye.  Students discuss how to estimate the effect of different variables on their star counts, such as sky brightness, dark adaptation, cloud cover, etc.
E-5. Follow the Falling Meteorite
More Universe at Your Fingertips ASP* 
book Students use demonstrations and data to locate a fallen meteorite by triangulation
Scientific Notation
IEER Classroom
webpaper Why use scientific notation, how it works, and how to do it, with a printable worksheet.
Andromeda's Scale


webpaper  Measure objects by angular size and distance. Then find the angular size of Andromeda by examining images of different angular size to find the right scale.
G-5. Light Travel Time and Earth History
More Universe at Your Fingertips ASP*
book Students calculate the dates when light left different objects in the sky (including some of the best known stars). They then do research to relate the dates to some significant event in the Earth's social or geologic history.

*Astronomical Society of the Pacific Ordering info $$


**Microwave Anisotropy Probe

Resources Access Description
Scientific Notation Drills:

Scientific to Decimal

Decimal to Scientific

web Java applets for converting back and forth, with instant feedback on your answers. Students should be instructed to type in their answers *before* checking!
Teacher's Guide to the Universe

sections 13-23


web Click to the Table of contents to find background and activities on measurement in astronomy (apparent size, distance) and the size of the Universe. Many are paper and pencil activities, and the structure of presentation is left to the teacher. May work best with the most motivated students.
Basic Geometry basic
Wellesley College
web "This is a short review of the geometric concepts and formulae that you will need for your Introductory Astronomy Course."