Description

This simulation is designed to help the user become familiar with the celestial coordinates used in astronomy. The left view shows the celestial sphere on which sit the stars. The observer's horizon plane is shown in green, with cardinal directions indicated. Optional controls allow the user to display gridlines for celestial coordinates (right ascension and declination), the celestial equator, the celestial colures (equinoctial and solstitial), and the vernal equinox point (the origin of the celestial coordinate system). In addition, the user can display a pointer that can be set to point to a location with a user-specified right ascension and declination, as well as the path that point will follow across the sky. The latitude for the observer can also be set. The user can also display the gridlines for local coordinates.

The right view shows a "star map" depicting the night sky as seen by the observer. Many features shown in the celestial sphere view on the left will be translated into this Sky View on the right, including the equator, pointer, pointer path, and local grid.

Finally, the user can select a specific real star to be highlighted in red using the drop-down menu. The menu lists the 20 brightest stars in decreasing order of apparent brightness.