ephem 日历库
import ephem
import datetime
now_datetime = datetime.datetime.now()
now_ephem = ephem.Date(now_datetime)
print "Datetime: ", now_datetime
print "Ephem : ", now_ephem
'%f' % ephem.Date('2013/12/20 12:34:56')
=> '41627.024259'
'%f' % ephem.Date('2013/12/20 12:34:56.1')
=> '41627.024260'