AstroApps

List of JavaScript Apps about astronomy

One focus of the following apps is to present the basics of astronomy in a graphically appealing way. After a click on Start Application a new window opens with the respective app. A short help can be found in the upper right corner under ''Help''.

Apps in 3D representation can rotate the view of the virtual camera using the left mouse button. The middle mouse button or the mouse wheel changes the distance to the current "point-of-interest" (PoI). The right mouse button can be used to move the camera parallel to the viewing plane. Further setting parameters can be found by clicking on the ▶ symbol in the upper left corner.

The visual representation is based on the graphics programming interface WebGL and especially the threejs-library. The d3js library is also used in some cases. Further information about the sources used can be found in "About".

Star Trails

With the app "Star Trails" you can visualize the apparent course of the stars on the celestial sphere. At various locations on Earth, you can display the visible part of the celestial sphere and follow the course of various stars on it. Real data and a free movement of the camera in 3D allow a variety of uses: rotation of the Earth as the reason for the apparent movement, influence of the observation location, rising and setting, (upper) culmination, circumpolar stars.

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Seasons

The obliquity of the Earth's axis by about 23.5° is the reason why there are seasons on Earth.

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Moon Phases

The app "Moon Phases" shows the movement of the Moon around the Earth illuminated by the Sun from a freely selectable perspective. This allows you to visualize not only the formation of the moon phases and the bound rotation of the moon, but also the (rare) occurrence of eclipses. By skilful choice of the observation time, the simulation speed and the object scales, the orbital period and the rotation period of the moon as well as the shape, size and orientation of the moon's orbit can be determined.

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Solar Eclipse

The orbital plane of the Moon around the Earth is slightly tilted compared to the orbital plane of the Earth around the Sun. Therefore, the Moon's shadow does not hit the Earth every time there is a full moon. Only at rare constellations, precisely when the connecting line between the Sun and the Moon (shadow ray) hits the Earth, can a solar eclipse be experienced from certain places on Earth.

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Horizontal Sundial

The horizontal sundial can display the time at the respective location via the shadow of a rod. Either a dial can be displayed that shows the true solar time for a certain longitude and latitude, or one that shows the actual UTC time.

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Stellar Parallax

If one observes the position of a nearby star in the course of a year, it appears to change against the background of very distant stars (celestial sphere). Depending on the distance of the star to the observer, this parallax takes a different angle.

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Orbital Elements

Orbital elements uniquely describe the location of a planet on its orbit around the Sun.

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Constellations in 3D

Constellations are only a two-dimensional projection of the actual locations of stars on the celestial sphere.

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Constellations in 3D - V2

Constellations are only a two-dimensional projection of the actual locations of stars on the celestial sphere. This version starts with all constellations and highlights individual ones.

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Radial-Velocity-Method

Exoplanet detection with the radial-velocity method.

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Transit method

Exoplanet detection with the transit method.

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Bright Stars in the HRD

The app "Bright Stars in the HRD" enables the transition from the observation of stars as simple light sources of a known starry sky to objects with physical properties. The step-by-step entry of pairs of values (luminosity and surface temperature) into a diagram results in an arrangement of data points that leads to the Hertzsprung-Russell diagram. The HRD is considered as a state diagram of the stars. The stellar evolution, on the other hand, is not the subject of this app.

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Cosmological Expansion

Are we at the center of the universe?

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Hubble-Lemaître relation

The Hubble-Lemaître relation links the distance to an object with its redshift. This app makes it possible explore the Hubble-Lemaître relation for yourself - namely, select galaxies in the sky for which the required data are available; the data points are then automatically entered into a corresponding diagram.

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Gravitational Lenses

Masses curve the space-time and light follows this curved space-time and is deflected thereby. If there is a large mass between us and a distant object, the object appears distorted due to the deflection of light.

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Stars around the galactic Black Hole

How S-Stars orbit around the black hole at the center of the Milky Way umkreisen

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