nasa’s mysteries of the universe: dark matter janet moore nasa educator ambassador janet moore...
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NASA’s Mysteries of the Universe:
Dark Matter
Janet MooreNASA Educator Ambassador
Merry-Go-Round
Merry-Go-Round
Solar System
Solar System
Solar System
Solar System
In Summary - Solar SystemOrbital speed
depends on force of gravity
Force of gravity depends on mass within the radius
Therefore, orbital speed depends on mass within the radius
What About Galaxies?
How would you expect stars to move around in a spiral galaxy?
What would you expect the mass distribution in a spiral galaxy to be?
The Activity - NGC 2742
You will be given:Rotation Curve
(velocity vs. radius)Luminosity Curve
(luminosity vs. radius)
Use the Data Chart to analyze the mass in the galaxy
G = 4.31 x 10-6
Sample Data ChartRadiu
sRot. Vel.
Grav. Mass
Lum. Lum. Mass
Lum/Grav
1 80 1.5 e9 3 e8 6 e8 0.4
3 100 6.9 e9 1 e9 2 e9 0.29
5 120 1.7 e10
2 e9 4 e9 0.24
8 140 3.6 e10
3.5 e9 7 e9 0.19
Evidence for Dark Matter
Light (visible matter) drops off as you go farther out in a galaxy
BUT . . . Velocities do not drop off
Result: Dark Matter mass is about 10x Luminous Matter mass
What is Dark Matter?Baryonic (Normal) Matter:
Low mass stars, brown dwarfs (likely), large planets, meteoroids, black holes, neutron stars, white dwarfs, hydrogen snowballs, clouds in halo.
Non-Baryonic (Exotic) Matter:Hot Dark Matter: fast-moving at time of
galaxy formation, eg massive neutrinosCold Dark Matter: slow-moving at times of
galaxy formation, eg WIMPs -- particle detector experiments looking for them
NASA’s Fermi Mission
Common Core Mathematical Practices
Make sense of problems and persevere in solving them.
Reason abstractly and quantitatively.
Construct viable arguments and critique the reasoning of others.
Model with mathematics. Use appropriate tools strategically. Attend to precision. Look for and make use of structure. Look for and express regularity in
repeated reasoning.
Mathematical modeling 1. Observing a phenomenon, delineating the problem
situation inherent in the phenomenon, and discerning the important factors that affect the problem.
2. Conjecturing the relationships among factors and interpreting them mathematically to obtain a model for the phenomenon.
3. Applying appropriate mathematical analysis to the model. 4. Obtaining results and reinterpreting them in the context
of the phenomenon under study and drawing conclusions.
Swetz, F., & Hartzler, J. S. (1991). Mathematical modeling in the secondary school curriculum: A resource guide of classroom exercises. (pp. 2-3). Reston, VA: National Council of Teachers of Mathematics.
Questions?
Janet Moore
epo.sonoma.edu