def moon_phase(time):
"""
Input: astropy.time.Time object
calculates number of days until full moon using pyephem
"""
Apache = ephem.Observer()
Apache.lat = APACHE.latitude.value
Apache.lon = APACHE.longitude.value
Apache.elevation = APACHE.height
Apache.date = time.iso
m = ephem.Moon(Apache)
#days until next full moon
full = ephem.next_full_moon(time.iso)
full = Time(full.datetime())
time_diff = abs(full - time)
days_to_full = time_diff.sec / 86400.
return days_to_full
