Change in Venus Express's Local Time at Ascending Node (31 March 2013 to 20 July 2013)
This figure shows the Local Time at Ascending Node (LTAN) during the period from 31 March 2013 to 20 July 2013 (medium term plan (MTP) 91 through MTP 94).
The Local Time at Ascending Node (LTAN) is the local time at which the spacecraft passes the Venusian equator on the ascending branch of its orbit. Values of 6:00 hrs and 18:00 hrs represent sunrise and sunset, respectively, and are on the terminator. LTAN values of 00:00 hrs and 12:00 hrs represent midnight and noon, respectively.
As on Earth, standard time zones are defined by geometrically subdividing Venus' spheroid into 24 wedge-shaped sections bordered by meridians, each 15° of longitude apart. The local time in neighbouring zones would differ by one Venus hour, or 1/24th of a Venus day. The variation in the position of the Sun from one end of the zone to the other (east vs. west) would be 1/24th of the sky.