Constellations are determined by the date of the solar calendar. On July 20th, 2002, the solar calendar date is August 28th, and the constellation of that day is Virgo.
Lunar calendar: July 20th, Renwu year.
Branch: Renwu Wu Shen Chen Wu
Gregorian calendar: Wednesday, August 28th, 2002, Virgo.
Source: Hua.com.