The Scale of the Universe
Discovering Our Place Among the Galaxies
Part II: New Tools and New Questions
Explore these simulations to gain a better understanding of the
material in Part II of The Scale of the Universe.
- Spectrum of Light Passed
Through a Gas:
Color image of the spectrum of light passed through a gas.
- Dark Sky Finite Age:
Illustrates how a finite age for stars explains the darkness of our
night sky.
- Radial Velocity Measurement:
Illustrates how the Doppler shift of spectral lines can be measured
in order to determine the radial velocity of an object.
- Stellar Blackbody Spectrum:
View the blackbody spectra of stars with different surface
temperatures, as well as a depiction of the star's overall color.
- Kapteyn Proper Motion:
Demonstrates Jacobus Kapteyn's analysis of the proper motion of
stars, and specifically how proper motions are distributed relative to
the line running from the antapex to the apex of the sun's motion,
by which he discovered the phenomenon of star streaming.
- Spiral Nebula Rotation:
Demonstrates van Maanen's method for measuring the rotation rate of
spiral nebulae by comparing photographs taken at two different times.
- Leavitt Cepheids:
Simulates Leavitt's measurement of the variation in apparent
magnitude of Cepheids with different periods in the Magellanic
Clouds. Data can be used to produce a plot similar to Leavitt's
original period-luminosity relation. Also features a way of plotting
the apparent magnitudes modulo a proposed period in order to precisely
determine the period of the variable star.
- Shapley Globular Clusters:
Illustrates the distribution of 69 globular clusters found by
Shapley in 1918, which formed the basis of his new model of the Milky
Way known as the Big Galaxy. Includes controls to adjust for the
effects of absorption in the galactic plane.