Mars Geocentric Distance

Local Time:The current local time.
Universal Time:Standardized time calculated by the rotation of the Earth.
Julian Day:Number of days since the year 4712 B.C.
Distance:The current distance of Mars to Earth. 1 A.U. (Astronomical Unit) is equal to approx. 93 million miles.

Light Time:The time it takes for reflected light to travel from Mars to Earth.
Calculation Time:The time required for the system to perform the iterations and display the distance. Although this time is not factored into the equations it will yield a small error in real-time distance.

Miles are displayed in blue while Mars is approaching, and will become red as it moves farther from Earth. Place your cursor over the underlined words for useful definitions. Distance calculated using VSOP87. Algorithms by Horace Dale. Javascript by Scott Meves.

Photo by H.Dale,
Emory University. 26 August 2003.