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6cd5dc91f6
wee_resources becomes weewx_data, and is put in version control. The build documentation, as well as the 'user' subdirectory, are now in it. This allows weewxd to be run directly from the git repository for two reasons: 1) the documentation does not have to be built first. 2) because the source code is now under 'src', while the 'user' subdirectory is in weewx_data, weewxd does not accidentally pick up the repository's version of the 'user' subdirectory.
51 lines
1.6 KiB
Python
51 lines
1.6 KiB
Python
#
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# Copyright (c) 2009-2023 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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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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