The table below contains a crude categorization scheme and pointers to simulations in both the NAAP and ClassAction packages. Thumbnails are available if you need to have your memory jogged. In ClassAction look under the Animations tab where simulations are organization by topic. In NAAP the simulations are a mixture of simulations that run in their own Native App windows and a few small ones are actually embedded in a web page. The table reflects a desire to retain the previous organization schemes while effectively pushing both of them together.
| Topic | Title | ClassAction Executable | NAAP Executable | Description | Thumbnail |
|---|---|---|---|---|---|
| Basic Motions & Ancient Astronomy | Small-Angle Approximation Demonstrator | CA-Basic Motions & Ancient Astronomy | Shows how small angles can be approximated. | Link | |
| Basic Motions & Ancient Astronomy | Heliacal Rising Simulator | CA-Basic Motions & Ancient Astronomy | Demonstrates how the day of the year when a star is first visible in the morning (the heliacal rising) depends on the observer's latitude and the star's position on the celestial sphere. | Link | |
| Basic Motions & Ancient Astronomy | Big Dipper Clock | CA-Basic Motions & Ancient Astronomy | Shows how stars rotate around the North Star over time (both daily and seasonal motions are shown). | Link | |
| Basic Motions & Ancient Astronomy | Ptolemaic System Simulator | NAAP-Solar Systems Models | Demonstrates how Ptolemy's geocentric model accounts for the movements of the planets. | Link | |
| Coordinates and Motions | Meridional Altitude Simulator - 2D | CA-Coordinates and Motions | Shows the geometry for calculating the meridional altitude of objects. | Link | |
| Coordinates and Motions | Meridional Altitude Simulator - 3D | NAAP - Motions of the Sun - Meridional Altitude Page | Shows the geometry in a horizon diagram for calculating the meridional altitude of objects. | Link | |
| Coordinates and Motions | Declination Ranges Simulator | CA-Coordinates and Motions | Shows how an observer's latitude determines the circumpolar, rise and set, and never rise regions in the sky. | Link | |
| Coordinates and Motions | Ecliptic Simulator | CA-Coordinates and Motions | Shows how the sun's declination and right ascension change over the course of a year. | Link | |
| Coordinates and Motions | Union Seasons Demonstrator | CA-Coordinates and Motions | Demonstrates the changing declination of the sun with a time-lapse movie, which shows how the shadow of a building changes over the course of a year. | Link | |
| Coordinates and Motions | Azimuth/Altitude Demonstrator | CA-Coordinates and Motions | Demonstrates the horizon coordinate system, where altitude and azimuth define an object's position in the sky. | Link | |
| Coordinates and Motions | Daylight Simulator | CA-Coordinates and Motions | Simulation showing daylight and nighttime regions on a flat map of Earth. Daily and yearly motions of the sunlight pattern can be shown. | Link | |
| Coordinates and Motions | Obliquity Simulator | CA-Coordinates and Motions | Shows how obliquity (orbital tilt) is defined. | Link | |
| Coordinates and Motions | Ecliptic (Zodiac)Simulator | CA-Coordinates and Motions | NAAP - Motions of the Sun | Shows the sun's position in the sky relative to the background stars (the zodiac constellations) over the course of a year. | Link |
| Coordinates and Motions | Longitude/Latitude Demonstrator | CA-Coordinates and Motions | Demonstrates latitude and longitude with an interactive globe, providing an analogy to the celestial and horizon coordinate systems. | Link | |
| Coordinates and Motions | Flat Map Explorer | NAAP-Basic Coordinates and Seasons | Demonstrates latitude and longitude on an interactive flat map of Earth. | Link | |
| Coordinates and Motions | Celestial-Equatorial (RA/Dec) Demonstrator | CA-Coordinates and Motions | Demonstrates the celestial-equatorial (RA/dec) coordinate system, where declination and right ascension define an object's position on the celestial sphere. | Link | |
| Coordinates and Motions | Flat Sky Map Explorer | NAAP-Basic Coordinates and Seasons | Demonstrates latitude and longitude on an interactive flat map of the celestial sphere. | Link | |
| Coordinates and Motions | Paths of the Sun | CA-Coordinates and Motions | Shows how the declination of the sun varies over the course of a year using a horizon diagram. | Link | |
| Coordinates and Motions | Sun Motions Overview | CA-Coordinates and Motions | NAAP - Motions of the Sun - Sun Paths Page | Shows the paths of the sun on the celestial sphere. | Link |
| Coordinates and Motions | Sun Motions Demonstrator, Motions of the Suns Simulator | CA-Coordinates and Motions | NAAP-Motions of the Sun | Models the motions of the sun in the sky using a horizon diagram, demonstrating daily and seasonal changes in the sun's position. | Link |
| Coordinates and Motions | Sun's Rays Simulator | CA-Coordinates and Motions | Shows how the sun's most direct rays hit different parts of the earth as the seasons change. | Link | |
| Coordinates and Motions | Sun's Position on Horizon | CA-Coordinates and Motions | Shows how the direction of the sun at sunrise or sunset changes over the course of the year. | Link | |
| Coordinates and Motions | Big Dipper 3D | CA-Coordinates and Motions | Demonstrates how the stars of the big dipper, which are at various distance from earth, project onto the celestial sphere to give the familiar asterism. | Link | |
| Coordinates and Motions | Seasons Simulator | CA-Coordinates and Motions | NAAP-Basic Coordinates and Seasons | Shows the geometry of Earth and Sun over the course of a year, demonstrating how seasons occur. This simulator allows both orbital and celestial sphere representations of the seasonal motions. | Link |
| Coordinates and Motions | Coordinate Systems Comparison, Rotating Sky Explorer | CA-Coordinates and Motions | NAAP-The Rotating Sky | Shows how the rotation of the earth leads to the apparent rotation of the sky, and how celestial sphere and horizon diagram representations of the sky are correlated. | Link |
| Coordinates and Motions | Daylight Hours Explorer | CA-Coordinates and Motions | Shows the hours of daylight received during the year for an observer at a given latitude. This is an important factor contributing to the seasons. | Link | |
| Coordinates and Motions | Antipodes Explorer | CA-Coordinates and Motions | Demonstrates antipodal points, which are points on opposite sides of Earth from each other. | Link | |
| Coordinates and Motions | Sidereal Time and Hour Angle Demonstrator | CA-Coordinates and Motions | Shows how sidereal time and the hour angle of a star are related. | Link | |
| Coordinates and Motions | Celestial and Horizon Systems Comparison | CA-Coordinates and Motions | Demonstrates how the celestial sphere and horizon diagram are related. | Link | |
| Coordinates and Motions | Sidereal and Solar Time Simulator | CA-Coordinates and Motions | NAAP-Motions of the Sun | Helps demonstrate the difference between sidereal and solar time. | Link |
| Coordinates and Motions | Bands in the Sky | NAAP - The Rotating Sky - Bands in the Sky Page | Show a horizon diagram for a certain latitude and the bands (logcations) in the sky where the sun, moon, and planets can be found. | Link | |
| Lunar Cycles | Lunar Phase Vocabulary | CA-Lunar Cycles | Shows the appearance of the moon at each of the named moon phases. | Link | |
| Lunar Cycles | Basketball Phases Simulator | CA-Lunar Cycles | Shows an illuminated basketball that can be viewed from multiple directions, providing an analogy to moon phases. | Link | |
| Lunar Cycles | Three Views Simulator | CA-Lunar Cycles | Shows how the phase of the moon depends on the viewing geometry by allowing the moon to be viewed from the earth, the sun, and an arbitrary point in space. | Link | |
| Lunar Cycles | Lunar Phases Simulator | CA-Lunar Cycles | NAAP-Lunar Phase Simulator | Demonstrates the correspondence between the moon's position in its orbit, its phase, and its position in an observer's sky at different times of day. | Link |
| Lunar Cycles | Moon Inclination | CA-Lunar Cycles | Demonstrates how the inclination of the moon's orbit precludes eclipses most of the time, leading to distinct eclipse seasons. | Link | |
| Lunar Cycles | Eclipse Table | CA-Lunar Cycles | Consists of a table of solar and lunar eclipses, showing the banding that represents the eclipse seasons that occur about twice a year. | Link | |
| Lunar Cycles | Eclipse Shadow Simulator | CA-Lunar Cycles | Provides draggable earth and moon discs with shadows, which can be used to demonstrate how the umbral (complete) and penumbral (partial) shadows give rise to different types of eclipses. | Link | |
| Lunar Cycles | Tidal Bulge Simulation | CA-Lunar Cycles | Shows how the sun, moon, and earth's rotation combine to create tides. | Link | |
| Lunar Cycles | Phase Positions Demonstrator | CA-Lunar Cycles | Demonstrates how planet and moon phases depend on orbital geometry. Users can drag two bodies around to see how the observed appearances change. | Link | |
| Lunar Cycles | Moon Phases and the Horizon Diagram | CA-Lunar Cycles | NAAP-Lunar Phase Simulator | Provides a method of learning the correlation between the phase of the moon, the time of day, and the position of the moon in the sky. | Link |
| Lunar Cycles | Synodic Lag | CA-Lunar Cycles | Demonstrates the difference between a sidereal and synodic (solar) day, which arises from Earth's revolution around the sun. | Link | |
| Lunar Cycles | Full Moon Declination Simulator | CA-Lunar Cycles | Shows the declination range of the full moon over the course of a year, and the corresponding changes in altitude for a northern hemisphere observer. | Link | |
| Lunar Cycles | Lunar Phase Quizzer | CA-Lunar Cycles | Shows the standard orbital view of the Moon, but with the option to hide the Moon's phase, the Moon's position, or the Sun's direction. | Link | |
| Lunar Cycles | Moon Phases With Bisectors | CA-Lunar Cycles | NAAP-Lunar Phase Simulator | Demonstrates a method for determining moon phases using planes that bisect the earth and moon. | Link |
| Renaisance Astronomy | Phases of Venus | CA-Renaissance Astronomy | Shows what Venus looks like through a telescope as the planets go around in their orbits. | Link | |
| Renaisance Astronomy | Ptolemaic Phases of Venus | CA-Renaissance Astronomy | Shows what Venus would look like through a telescope if Ptolemy's model was correct. Compare with the other Phases of Venus simulation. | Link | |
| Renaisance Astronomy | Ptolemaic Orbit of Mars | CA-Renaissance Astronomy | Shows Ptolemy's model for the orbit of Mars. | Link | |
| Renaisance Astronomy | Epicycles Demo | CA-Renaissance Astronomy | Demonstrates that the heliocentric and geocentric models are equivalent for predictive purposes when limited to circular orbits. | Link | |
| Renaisance Astronomy | Copernican Solar System | NAAP - Solar Systems Models - Heliocentrism | A simple animation showing the circular orbits of the 6 inner planets around the Sun. | Link | |
| Renaisance Astronomy | Retrograde Motion | CA-Renaissance Astronomy | Demonstrates the retrograde motion of Mars with an annotated animation. | Link | |
| Renaisance Astronomy | Kepler's Third Law | CA-Renaissance Astronomy | Lets one calculate the period of a planet from its semimajor axis, and vice versa. | Link | |
| Renaisance Astronomy | Synodic Period Calculator | CA-Renaissance Astronomy | Lets one calculate the sidereal period of the planet (P) from the synodic period (S), and vice versa. | Link | |
| Renaisance Astronomy | Planetary Configurations Simulator | CA-Renaissance Astronomy | Models the movements of the planets around the sun in a simplified Copernican model of the solar system. | Link | |
| Renaisance Astronomy | Planetary Orbit Simulator | CA-Renaissance Astronomy | NAAP-Planetary Orbits | Models the motion of a hypothetical planet that orbits the sun according to Kepler's laws of motion. This simulator includes controls for investigating each of Kepler's laws. | Link |
| Renaisance Astronomy | Eccentricity Demonstrator | CA-Renaissance Astronomy | NAAP - Planetary Orbits - Kepler's Laws of Planetary Motion Page | Demonstrates the parameters that define the eccentricity of an ellipse. | Link |
| Renaisance Astronomy | Earth Orbit Plot | CA-Renaissance Astronomy | Shows the orbital period as a function of orbital distance for satellites of Earth. | Link | |
| Renaisance Astronomy | Newton's Law of Gravity Calculator | CA-Renaissance Astronomy | Allows one to calculate the force of gravity acting on a variety of masses over a range of distances. | Link | |
| Renaisance Astronomy | Gravity Algebra | CA-Renaissance Astronomy | Shows how the force of gravity would be different if the values used in Newton's law of universal gravitation formula are changed. | Link | |
| Renaisance Astronomy | Projectile (Escape Velocity) Simulation | NAAP - Atmopheric Retention | Allow you to shoot projectiles with various speeds away from various solar system bodies and iteratively determine their escape speed. | Link | |
| Light & Spectra | Blackbody Curves of Melting | CA-Light & Spectra | Light & Spectra | A movie showing the heating and eventual melting of a nail, and the theoretical blackbody curve produced in the process. | Link |
| Light & Spectra | Spectrum Explorer | CA-Light & Spectra | Light & Spectra | Allows one to generate a variety of simulated spectra, depending on factors such as the type of source, luminosity class, spectral type, and individually selected elements. | Link |
| Light & Spectra | EM Spectrum Module | CA-Light & Spectra | Light & Spectra | Surveys the electromagnetic spectrum, showing a typical astronomical image for different wavelengths of light and the kind of instrument that would take such an image. | Link |
| Light & Spectra | Comparison of Three Blackbody Curves | Light & Spectra | NAAP-Blackbody Curves and UBV Simulator - Spectral Types of Stars Page | Allows the users to change the scale illustrating the blackbody curves for a 3000K, 6000K, and 12,000 K object. | Link |
| Light & Spectra | Blackbody Curves | CA-Light & Spectra | NAAP-Blackbody Curves and UBV Simulator | Demonstrates how the blackbody spectrum varies with temperature. This explorer also shows how the relative intensities observed through different filters (a 'color index') can give an estimate of temperature. | Link |
| Light & Spectra | Filters Simulator | CA-Light & Spectra | NAAP-Blackbody Curves and UBV Simulator | Demonstrates how different light sources and filters combine to determine an observed spectrum. This simulator also shows the perceived colors associated with the spectra shown. | Link |
| Light & Spectra | Hydrogen Atom Simulator | CA-Light & Spectra | NAAP - Hydrogen Energy Levels | Models a hydrogen atom and its interactions with light, demonstrating the quantum nature of absorption and emission. | Link |
| Light & Spectra | Hydrogen Energy Level Abundances | Light & Spectra | NAAP - Hydrogen Energy Levels - Level Abundances Page | Show the relative abundances of hydrogen atom electron levels for various temperatures. | Link |
| Light & Spectra | Three Views Spectrum Demonstrator | CA-Light & Spectra | Light & Spectra | Demonstrates how different spectra can arise from a light bulb (a thermal source) and a cold, thin gas cloud. The spectrometer shows emission, absorption, or continuous spectra based on where the draggable telescope is pointed. | Link |
| Light & Spectra | Extrasolar Planet Radial Velocity Demonstrator | CA-Light & Spectra | Light & Spectra | Demonstrates how the spectrum of a star is shifted as it and its planet orbit their common center of mass. | Link |
| Light & Spectra | Doppler Shift Demonstrator | CA-Light & Spectra | Shows circular waves expanding from a source. Movement of the source or observer affects the frequency of the waves seen by the observer, demonstrating doppler shift. | Link | |
| Telescopes and Astronomical Instruments | Telescope Simulator | CA-Telescopes and Astronomical Instruments | Telescopes and Astronomical Instruments | Demonstrates the properties of a telescope, and how these vary with aperture and eyepiece selection. | Link |
| Telescopes and Astronomical Instruments | CCD Simulator | CA-Telescopes and Astronomical Instruments | Telescopes and Astronomical Instruments | Shows a rainfall and bucket analogy to CCD imaging. | Link |
| Telescopes and Astronomical Instruments | Snell's Law Demonstrator | CA-Telescopes and Astronomical Instruments | Telescopes and Astronomical Instruments | Demonstrates Snell's Law, a formula that describes how light is refracted when it moves between different media. | Link |
| Telescopes and Astronomical Instruments | Registration Simulator | Telescopes and Astronomical Instruments | NAAP-Variable Star Photometry | Simulates the alignment of CCD frames and identifying the offsets so that objects are at overlying locations. | Link |
| Telescopes and Astronomical Instruments | Blink Comparator Simulator | NAAP-Variable Star Photometry | Allow one to succesively "blink" CCD frames to identify moving objects. | Link | |
| Telescopes and Astronomical Instruments | Photometry Simulator | NAAP-Variable Star Photometry | Allows one to perform differential photometery and calculate relative stellar magnitudes on a CCD frame. | Link | |
| Sun and Solar Energy | Proton-Proton Animation | CA-Sun and Solar Energy | Shows an animated diagram of the proton-proton chain reaction, which is the dominant fusion reaction in the sun's core. | Link | |
| Sun and Solar Energy | CNO Cycle Animation | CA-Sun and Solar Energy | Shows an animated diagram of the CNO cycle, which dominates in stars larger than the sun. | Link | |
| Stellar Properties | Distance Modulus Explorer | CA-Stellar Properties | Stellar Properties | Shows how the distance modulus formula combines apparent and absolute magnitudes to give the distance to a star. | Link |
| Stellar Properties | Stellar Velocity Calculator | CA-Stellar Properties | Stellar Properties | Shows how the distance to a star, its doppler shift, and its proper motion allow one to calculate the star's true space velocity. | Link |
| Stellar Properties | Stellar Luminosity Calculator | Stellar Properties | NAAP - Hertzsprung-Russell Diagram - Luminosity Page | Shows how the luminosity of a star depends upon its surface temperature and radius. | Link |
| Stellar Properties | Parallax Calculator | CA-Stellar Properties | Stellar Properties | Diagrams the geometry and shows the math involved in determining a star's distance via parallax. | Link |
| Stellar Properties | Parallax Explorer | Stellar Properties | NAAP - Cosmic Distance Ladder | Allow one to experiement with parallax using different baselines and errors in the observations. | Link |
| Stellar Properties | Spectroscopic Parallax Simulator | CA-Stellar Properties | NAAP - Cosmic Distance Ladder | Demonstrates how the technique of spectroscopic parallax works.Spectral type and luminosity class determine the observed spectrum of a star, from which the star's luminosity can be estimated. | Link |
| Stellar Properties | Stellar Luminosity Calculator | CA-Stellar Properties | Stellar Properties | Demonstrates how a star's luminosity depends on its temperature and radius. | Link |
| Stellar Properties | Flux Simulator | CA-Stellar Properties | Stellar Properties | Demonstrates the inverse square law of light with a lightbulb and detector. | Link |
| Stellar Properties | HR Explorer | CA-Stellar Properties | Stellar Properties | Introduces the Hertzsprung-Russell Diagram, a plot showing the relationship between luminosity and temperature for stars. | Link |
| Stellar Properties | HR Diagram Star Cluster Fitting Explorer | NAAP - Cosmic Distance Ladder | Allows determining the distance to a cluster by fitting the cluster's stars to the main sequence in an HR diagram. | Link | |
| Binary and Variable Stars | Eclipsing Binary Simulator | CA-Binary and Variable Stars | NAAP-Eclipsing Binary Simulator | Models the motions of two stars in orbit around each other, and the combined lightcurve they produce. This simulator allows the user to control multiple parameters to see how they effect the lightcurve. Includes several real datasets. | Link |
| Binary and Variable Stars | Aliasing in Wagon Wheels | CA-Binary and Variable Stars | Binary and Variable Stars | Demonstrates aliasing through the analogy of a wagon wheel being filmed. For some combinations of frame rates and true rotation speeds the wheel can appear to rotate backwards. | Link |
| Binary and Variable Stars | Center of Mass Simulator | CA-Binary and Variable Stars | NAAP - Eclipsing Binary Stars - Center of Mass Page | Shows how the center of mass of two objects changes as their masses change. | Link |
| Binary and Variable Stars | Lightcurve Simulator | CA-Binary and Variable Stars | NAAP - Eclipsing Binary Stars - Light Curves Page | Shows how a lightcurve is constructed from observations of an eclipsing binary system. | Link |
| Binary and Variable Stars | Variable Star Photometry Analyzer | CA-Binary and Variable Stars | NAAP-Variable Star Photometry | Centerpiece for an advanced lab on variable star photometry. | Link |
| Milky Way Galaxy | Milky Way Rotational Velocity | CA-Milky Way Galaxy | A plot of the rotational velocity of stars at varying distances from the center of the milky way. A draggable cursor allows determining the contained mass implied by the curve. | Link | |
| Milky Way Galaxy | Traffic Density Analogy | CA-Milky Way Galaxy | The build-up of traffic behind a slow moving tractor provides an analogy to the density wave formation of spiral arms. | Link | |
| Cosmology | Lookback Time Simulator | CA-Introductory Concepts | An animation of coins attached to a balloon, providing an analogy to the expansion of the universe. The coins represent galaxies, which maintain their scale while the space between them grows. | Link | |
| Cosmology | Balloon Universe | CA-Cosmology | An animation of coins attached to a balloon, providing an analogy to the expansion of the universe. The coins represent galaxies, which maintain their scale while the space between them grows. | Link | |
| Cosmology | Galactic Redshift Simulator | CA-Cosmology | Demonstrates the redshift of a galaxy due to the expansion of the universe, and the effect this shift has on the galaxy's brightness as observed through various filters. | Link | |
| Cosmology | Supernova Light Curve Fitting Explorer | NAAP - Cosmic Distance Ladder | Allows determining the distance to a supernova by fitting observations to a theoretical Type Ia curve. | Link | |
| Solar System | Planet Formation Temperatures Plot | CA-Solar System Characteristics | Shows planet formation temperature as a function of distance from the Sun. Also indicates the state (gas or solid) of several substances at the given distance and temperature. | Link | |
| Solar System | Solar System Properties Explorer | CA-Solar System Characteristics | Allows one to explore a set of histograms for characteristics like number of satellites, mass, orbital period, etc. for the terrestial and jovian planets, plus Pluto. | Link | |
| Solar System | Maxwell Distribution | NAAP - Atmospheric Retention | Simple animation shows the distribution of the speeds of gas particles. | Link | |
| Solar System | Gas Retention Plot | NAAP - Atmospheric Retention | Shows how the molecular mass, temperature, and escape speed determine whether a gas will remain gravitationally bound to a planet. | Link | |
| Solar System | Gas Retention Simulator | NAAP - Atmospheric Retention | Demonstrates how gases of different molecular masses behave when maintained at thermodynamic equilibrium in a chamber. The chamber can be set to allow particles that exceed a certain speed to escape, providing an analogy for the bleeding of a planet's atmosphere into space. | Link | |
| Solar System | Driving Through Snow | CA-Animations | Shows a snow shower from the perspective of a car driving through it, demonstrating how the snow seems to diverge from some central point (the radiant). Provides an analogy to a meteor shower. | Link | |
| ExtraSolar Planets | Influence of Planets on the Sun | CA-Animations | NAAP - Atmospheric Retention | Shows the movement of the sun due to the gravitational pull of the planets. The contribution from each planet can be isolated by toggling checkboxes. | Link |
| ExtraSolar Planets | Radial Velocity Graph | CA-Animations | Shows a star and planet in orbit around each other while tracing out the star's radial velocity curve. | Link | |
| ExtraSolar Planets | Transit Simulator | CA-Animations | Demonstrates how a planet passing in front of its parent star can cause dips in the star's lightcurve, potentially leading to the planet's detection. | Link | |
| ExtraSolar Planets | Extrasolar Planet Radial Velocity Demonstrator | CA-Animations | Demonstrates how the spectrum of a star is shifted as it and its planet orbit their common center of mass. | Link | |
| ExtraSolar Planets | Radial Velocity Simulator | CA-Animations | Models the motion of an extrasolar planet and its star around their common center of mass, and the effect this motion has on the star's observed radial velocity. | Link | |
| ExtraSolar Planets | Pulsar Period Simulator | CA-Animations | Demonstrates how the movement of a pulsar and planet around their common center of mass affects the timing of pulse arrivals. | Link | |
| ExtraSolar Planets | Hammer Thrower Comparison | CA-Animations | Illustrates how the movement of a star and its planet about their center of mass compares to a hammer thrower swinging a heavy metal ball. | Link | |
| ExtraSolar Planets | Circumstellar Habitable Zone Simulator | NAAP - Habitable Zones | Demonstrates location and evolution of the stellar habitable zone, which is the region around a star where surface water may exist on a earth like planet. | Link | |
| ExtraSolar Planets | Milky Way Habitability Explorer | NAAP - Habitable Zones | Shows how two factors important to life – metallicity and extinction risk – vary throughout the Milky Way Galaxy. | Link |