Show times for dusk, dawn, sunset and sunrise.

twilight.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Usage: twilight.py [--city=<city> | --coordinates=<coordinates>]
                   [--date=<date> | --tomorrow] [--week]
                   [-h | --help | --version]

Options:
    -h --help       Show this help.
    --version       Show version.
    -d --date=<date> Set date, YYYY-MM-DD
    -t --tomorrow   Set date for tomorrow.
    -w --week       Show times for whole week (today + 7 days)
    --city=<city>   Set coordinates to following city (see ephem documentation)
    -c --coordinates=<latitude>,<longitude>
                    Set coordinates in  degrees
"""
import datetime
import docopt
import ephem
import math

__version__ = '0.1'
__author__ = 'Tomáš Ehrlich <tomas.ehrlich@gmail.com>'

arguments = docopt.docopt(__doc__, version=__version__)

coordinates_override = {
    'Brno': '49.19729,16.60362'
}

radians = lambda d: d*math.pi/180
local = lambda d: ephem.localtime(d)

TIME_FORMAT = '%H:%M:%S'
DATE_FORMAT = '%A %d. %B'

sun = ephem.Sun()

# Set location
coords = arguments.get('--coordinates', None)
city = arguments.get('--city') or 'Brno'
if city in coordinates_override:
    coords = coordinates_override[city]
if coords:
    obs = ephem.Observer()
    obs.lat, obs.lon = map(radians, map(float, coords.split(',')))
else:
    obs = ephem.city(city)

# Set date
date = arguments.get('--date', None)
if date:
    date = datetime.datetime.strptime(date, '%Y-%m-%d').date()
else:
    date = datetime.date.today()
    if arguments['--tomorrow'] and not arguments['--week']:
        date += datetime.timedelta(days=1)
day_range = arguments['--week'] and 7 or 1

print 'Location: {}, {}'.format(obs.lat, obs.lon)
for interval in range(day_range):
    obs.date = date + datetime.timedelta(days=interval)

    obs.horizon = '0'
    sunrise, sunset = map(local, (obs.next_rising(sun), obs.next_setting(sun)))
    obs.horizon = '-6'
    dawn, dusk = map(local, (obs.next_rising(sun), obs.next_setting(sun)))
    print obs.date.datetime().strftime(DATE_FORMAT)

    print 'Dawn:\t\t{}'.format(dawn.strftime(TIME_FORMAT))
    print 'Sunrise:\t{}'.format(sunrise.strftime(TIME_FORMAT))
    print 'Sunset: \t{}'.format(sunset.strftime(TIME_FORMAT))
    print 'Dusk:\t\t{}'.format(dusk.strftime(TIME_FORMAT))
    print

Thank you for this, it was exactly what I was looking for.