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earthDay      Reference Sheet


earthDay focuses on exploring the spatial environment surrounding the Earth, and provides a variety of ways of looking at the Earth, the moon, the artificial satellites, and the planets on a particular day at a particular time.




Binaries and documents



  • The Earth, Moon, and Sun with correct lighting

  • Visualization of the current time and day over the surface of the Earth to see the effect of the International Dateline.

  • Display of a wide selection of Earth-orbiting artificial satellites, including color coded satellite functions and a 3D model of the International Space Station.

  • Accurate simulation of umbra, penumbra, and Solar Eclipses. By turning on the various eclipse display options and selecting a date and time during an eclipse, one can get a very compelling visualization of the eclipse geometry. It is possible to look either up at the eclipse itself, or down at the shadows traversing the surface of the Earth.

  • Landmarks on Earth: major cities, time zones, flight paths, etc.

  • Planetary trajectories and simulation of retrograde motions with precise time control.

  • Sky context with stars , Milky Way and constellation lines



Data Sources:

Satellite, planet, and ephemeris data are based on JPL and NASA web sites, including,,, and

ISS space station model:

See also Astronomy Picture of the Day,, for an animation based on EarthDay.




Software development lead: Philip Chi-Wing Fu.  Additional software: Yinggang Li.  Documentation: Yinggang Li,  Philip Chi-Wing Fu, Andrew Hanson, Priscilla Frisch.  Supported in part by   “Journey of the Sun” NASA grants  NAG 5-8163, NAG 5-13558, NAG 5-11999, awarded to the University of Chicago with subcontractor Indiana University.


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