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# Conflicts: # bin/weecfg/test/expected/weewx39_user_expected.conf # bin/weewx/__init__.py # bin/weewx/manager.py # docs/changes.txt # weewx.conf
52 lines
1.6 KiB
Python
52 lines
1.6 KiB
Python
#
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# Copyright (c) 2009-2019 Tom Keffer <tkeffer@gmail.com>
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#
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# See the file LICENSE.txt for your full rights.
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#
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"""Given a date, determine the phase of the moon."""
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from __future__ import absolute_import
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import time
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import math
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moon_phases = ["new (totally dark)",
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"waxing crescent (increasing to full)",
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"in its first quarter (increasing to full)",
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"waxing gibbous (increasing to full)",
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"full (full light)",
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"waning gibbous (decreasing from full)",
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"in its last quarter (decreasing from full)",
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"waning crescent (decreasing from full)"]
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# First new moon of 2018: 17-Jan-2018 at 02:17 UTC
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new_moon_2018 = 1516155420
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def moon_phase(year, month, day, hour=12):
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"""Calculates the phase of the moon, given a year, month, day.
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returns: a tuple. First value is an index into an array
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of moon phases, such as Moon.moon_phases above. Second
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value is the percent fullness of the moon.
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"""
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# Convert to UTC
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time_ts = time.mktime((year, month, day, hour, 0, 0, 0, 0, -1))
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return moon_phase_ts(time_ts)
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def moon_phase_ts(time_ts):
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# How many days since the first moon of 2018
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delta_days = (time_ts - new_moon_2018) / 86400.0
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# Number of lunations
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lunations = delta_days / 29.530588
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# The fraction of the lunar cycle
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position = float(lunations) % 1.0
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# The percent illumination, rounded to the nearest integer
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fullness = int(100.0 * (1.0 - math.cos(2.0 * math.pi * position)) / 2.0 + 0.5)
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index = int((position * 8) + 0.5) & 7
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return index, fullness
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