Change in Venus Express's local time at ascending node (19 August to 8 December 2012)
This figure shows the Local Time at Ascending Node (LTAN) during the period from 19 August to 8 December 2012 (medium term plan (MTP) #83 through medium term plan (MTP) #86).
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 06:00 and 09:00 represent sun rise and sun set, respectively, and are on the terminator. LTAN values of 00:00 and 12:00 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.