Moon phases

A new moon happens when the moon passes between the earth and sun. Usually, the three bodies won't form a perfectly straight line. Rather, the moon passes a little north or south of the path the sun travels along. At first quarter, the moon, earth, and sun form a right angle with the western half of the moon's disk in sunlight. A full moon happens when the moon is on the opposite side of the sky as the sun. As with the new moon, the moon, earth, and sun don't usually form a perfectly straight line. Rather, the moon passes a little north or south of the point in the sky opposite the sun. Last quarter is when the eastern half of the moon's disk is lit up. The moon, earth, and sun again for a right angle.

One full cycle of lunar phases is called a lunation. A widely accepted count of lunation cycles began with the new moon of January 17, 1923. That was the start of astronomer Ernest William Brown's lunation number 1. There have been more than 1,100 lunation cycles since. The Brown lunation numbers are given below. There are other lunation cycle counts, however. Some were started for scientific purposes. Others were started for religious reasons. Astronomical computing expert Jean Meeus proposed referring to the new moon of January 6, 2000 as lunation 0. Computer scientist Herman Goldstine's lunation 0 begins on January 11, 1001 BC. The Islamic calendar's lunation 1 started on July 16, 622. And the Hebrew calendar lunation 1 began on September 7, 3761 BC.

Most people aren't concerned with counting lunar cycles except for curiosity. However, knowing how many such cycles have passed during a given time can be important in scientific discussions about the moon's orbit and in properly rendering religious calendars. To convert the Brown lunation number below to the Meeus number, substract 953. To obtain the Goldstine number, add 37,105. For the Islamic number, add 17,038. And for the Hebrew number, add 71,234.

The average length of a lunar cycle is 29 days, 12 hours, 44 minutes. The time between successive new moons or full moons will vary by a few minutes because of the gravitational tug the sun, moon, and earth have on each other. While one is inclined to think of this time as the length of the moon's orbit around the earth, the moon actually orbits in just 27 days, 12 hours. The moon completes an orbit when it returns to nearly the same position among the distant stars behind it from our view. But during that time, the earth moves. To get to the same position compared to the relatively close sun takes two more days.

Here are the dates and times in Universal Time for moon phases in the 2010 decade.

Year Lunation New Moon First Quarter Full Moon Last Quarter
2010  
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
 
January 15 - 07:12
February 14 - 02:52
March 15 - 21:02
April 14 - 12:29
May 14 - 01:05
June 12 - 11:15
July 11 - 19:41
August 10 - 03:09
September 8 - 10:30
October 7 - 18:45
November 6 - 04:52
December 5 - 17:36
 
January 23 - 10:54
February 22 - 00:43
March 23 - 11:01
April 21 - 18:20
May 20 - 23:43
June 19 - 04:30
July 18 - 10:11
August 16 - 18:15
September 15 - 05:50
October 14 - 21:28
November 13 - 16:39
December 13 - 13:59
 
January 30 - 06:18
February 28 - 16:38
March 30 - 02:26
April 28 - 12:19
May 27 - 23:08
June 26 - 11:31
July 26 - 01:37
August 24 - 17:05
September 23 - 09:18
October 23 - 01:37
November 21 - 17:28
December 21 - 08:14
January 7 - 10:40
February 5 - 23:49
March 7 - 15:42
April 6 - 09:37
May 6 - 04:15
June 4 - 22:14
July 4 - 14:36
August 3 - 04:59
September 1 - 17:22
October 1 - 03:53
October 30 - 12:46
November 28 - 20:37
December 28 - 04:19

2011 1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
January 4 - 09:03
February 3 - 02:31
March 4 - 20:46
April 3 - 14:33
May 3 - 06:51
June 1 - 21:03
July 1 - 08:54
July 30 - 18:40
August 29 - 03:05
September 27 - 11:09
October 26 - 19:56
November 25 - 06:10
December 24 - 18:07
January 12 - 11:32
February 11 - 07:19
March 12 - 23:45
April 11 - 12:06
May 10 - 20:33
June 9 - 02:11
July 8 - 06:30
August 6 - 11:09
September 4 - 17:40
October 4 - 03:16
November 2 - 16:39
December 2 - 09:53
January 19 - 21:22
February 18 - 08:36
March 19 - 18:11
April 18 - 02:44
May 17 - 11:09
June 15 - 20:14
July 15 - 06:40
August 13 - 18:58
September 12 - 09:27
October 12 - 02:06
November 10 - 20:17
December 10 - 14:37
January 26 - 12:58
February 24 - 23:27
March 26 - 12:08
April 25 - 02:47
May 24 - 18:53
June 23 - 11:49
July 23 - 05:02
August 21 - 21:55
September 20 - 13:39
October 20 - 03:31
November 18 - 15:10
December 18 - 00:48

2012  
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
 
January 23 - 07:40
February 21 - 22:35
March 22 - 14:38
April 21 - 07:19
May 20 - 23:47
June 19 - 15:03
July 19 - 04:25
August 17 - 15:55
September 16 - 02:11
October 15 - 12:03
November 13 - 22:09
December 13 - 08:42
January 1 - 06:15
January 31 - 04:10
March 1 - 01:22
March 30 - 19:41
April 29 - 09:58
May 28 - 20:17
June 27 - 03:31
July 26 - 08:57
August 24 - 13:54
September 22 - 19:41
October 22 - 03:32
November 20 - 14:32
December 20 - 05:20
January 9 - 07:31
February 7 - 21:54
March 8 - 09:40
April 6 - 19:19
May 6 - 03:36
June 4 - 11:12
July 3 - 18:52
August 2 - 03:28
August 31 - 13:59
September 30 - 03:19
October 29 - 19:50
November 28 - 14:46
December 28 - 10:22
January 16 - 09:08
February 14 - 17:04
March 15 - 01:26
April 13 - 10:50
May 12 - 21:47
June 11 - 10:42
July 11 - 01:48
August 9 - 18:55
September 8 - 13:15
October 8 - 07:34
November 7 - 00:36
December 6 - 15:32

2013  
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
 
January 11 - 19:44
February 10 - 07:21
March 11 - 19:51
April 10 - 09:36
May 10 - 00:29
June 8 - 15:57
July 8 - 07:15
August 6 - 21:51
September 5 - 11:37
October 5 - 00:35
November 3 - 12:50
December 3 - 00:23
 
January 18 - 23:45
February 17 - 20:31
March 19 - 17:27
April 18 - 12:31
May 18 - 04:35
June 16 - 17:24
July 16 - 03:19
August 14 - 10:56
September 12 - 17:09
October 11 - 23:03
November 10 - 05:58
December 9 - 15:12
 
January 27 - 04:39
February 25 - 20:27
March 27 - 09:28
April 25 - 19:58
May 25 - 04:25
June 23 - 11:33
July 22 - 18:16
August 21 - 01:45
September 19 - 11:13
October 18 - 23:38
November 17 - 15:16
December 17 - 09:29
January 5 - 03:58
February 3 - 13:57
March 4 - 21:53
April 3 - 04:37
May 2 - 11:15
May 31 - 18:59
June 30 - 04:54
July 29 - 17:44
August 28 - 09:35
September 27 - 03:56
October 26 - 23:41
November 25 - 19:28
December 25 - 13:48

2014 1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
January 1 - 11:15
January 30 - 21:39
March 1 - 08:00
March 30 - 18:45
April 29 - 06:15
May 28 - 18:41
June 27 - 08:09
July 26 - 22:42
August 25 - 14:13
September 24 - 06:14
October 23 - 21:57
November 22 - 12:33
December 22 - 01:36
January 8 - 03:40
February 6 - 19:23
March 8 - 13:27
April 7 - 08:31
May 7 - 03:15
June 5 - 20:39
July 5 - 11:59
August 4 - 00:50
September 2 - 11:12
October 1 - 19:33
October 31 - 02:49
November 29 - 10:07
December 28 - 18:32
January 16 - 04:53
February 14 - 23:54
March 16 - 17:09
April 15 - 07:43
May 14 - 19:16
June 13 - 04:12
July 12 - 11:25
August 10 - 18:10
September 9 - 01:39
October 8 - 10:51
November 6 - 22:23
December 6 - 12:27
January 24 - 05:20
February 22 - 17:16
March 24 - 01:47
April 22 - 07:52
May 21 - 13:00
June 19 - 18:39
July 19 - 02:09
August 17 - 12:26
September 16 - 02:05
October 15 - 19:13
November 14 - 15:16
December 14 - 12:51

2015  
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
 
January 20 - 13:14
February 18 - 23:48
March 20 - 09:37
April 18 - 18:57
May 18 - 04:14
June 16 - 14:06
July 16 - 01:25
August 14 - 14:54
September 13 - 06:42
October 13 - 00:06
November 11 - 17:48
December 11 - 10:30
 
January 27 - 04:49
February 25 - 17:14
March 27 - 07:43
April 25 - 23:56
May 25 - 17:19
June 24 - 11:03
July 24 - 04:05
August 22 - 19:32
September 21 - 09:00
October 20 - 20:32
November 19 - 06:28
December 18 - 15:15
January 5 - 04:54
February 3 - 23:09
March 5 - 18:06
April 4 - 12:06
May 4 - 03:43
June 2 - 16:19
July 2 - 02:20
July 31 - 10:43
August 29 - 18:36
September 28 - 02:51
October 27 - 12:06
November 25 - 22:45
December 25 - 11:12
January 13 - 09:47
February 12 - 03:50
March 13 - 17:48
April 12 - 03:45
May 11 - 10:37
June 9 - 15:42
July 8 - 20:24
August 7 - 02:03
September 5 - 09:55
October 4 - 21:07
November 3 - 12:24
December 3 - 07:41

2016  
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
 
January 10 - 01:31
February 8 - 14:39
March 9 - 01:55
April 7 - 11:24
May 6 - 19:30
June 5 - 03:00
July 4 - 11:02
August 2 - 20:45
September 1 - 09:04
October 1 - 00:12
October 30 - 17:39
November 29 - 12:19
December 29 - 06:54
 
January 16 - 23:27
February 15 - 07:47
March 15 - 17:03
April 14 - 04:00
May 13 - 17:03
June 12 - 08:10
July 12 - 00:52
August 10 - 18:21
September 9 - 11:49
October 9 - 04:33
November 7 - 19:52
December 7 - 09:04
 
January 24 - 01:46
February 22 - 18:20
March 23 - 12:01
April 22 - 05:24
May 21 - 21:15
June 20 - 11:03
July 19 - 22:57
August 18 - 09:27
September 16 - 19:06
October 16 - 04:24
November 14 - 13:53
December 14 - 00:06
January 2 - 05:31
February 1 - 03:28
March 1 - 23:11
March 31 - 15:17
April 30 - 03:29
May 29 - 12:13
June 27 - 18:19
July 26 - 23:00
August 25 - 03:41
September 23 - 09:57
October 22 - 19:14
November 21 - 08:34
December 21 - 01:56

2017  
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
 
January 28 - 00:07
February 26 - 14:59
March 28 - 02:58
April 26 - 12:17
May 25 - 19:45
June 24 - 02:31
July 23 - 09:46
August 21 - 18:31
September 20 - 05:30
October 19 - 19:13
November 18 - 11:43
December 18 - 06:31
January 5 - 19:48
February 4 - 04:19
March 5 - 11:33
April 3 - 18:40
May 3 - 02:47
June 1 - 12:43
July 1 - 00:52
July 30 - 15:24
August 29 - 08:13
September 28 - 02:54
October 27 - 22:23
November 26 - 17:03
December 26 - 09:21
January 12 - 11:35
February 11 - 00:33
March 12 - 14:54
April 11 - 06:09
May 10 - 21:43
June 9 - 13:10
July 9 - 04:07
August 7 - 18:11
September 6 - 07:03
October 5 - 18:41
November 4 - 05:23
December 3 - 15:48
January 19 - 22:14
February 18 - 19:34
March 20 - 15:59
April 19 - 09:57
May 19 - 00:33
June 17 - 11:33
July 16 - 19:26
August 15 - 01:16
September 13 - 06:25
October 12 - 12:26
November 10 - 20:37
December 10 - 07:52

2018  
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
 
January 17 - 02:18
February 15 - 21:06
March 17 - 13:12
April 16 - 01:58
May 15 - 11:48
June 13 - 19:44
July 13 - 02:48
August 11 - 09:58
September 9 - 18:02
October 9 - 03:47
November 7 - 16:03
December 7 - 07:21
 
January 24 - 22:21
February 23 - 08:10
March 24 - 15:36
April 22 - 21:46
May 22 - 03:50
June 20 - 10:51
July 19 - 19:53
August 18 - 07:49
September 16 - 23:16
October 16 - 18:02
November 15 - 14:55
December 15 - 11:50
January 2 - 02:25
January 31 - 13:27
March 2 - 00:52
March 31 - 12:37
April 30 - 00:59
May 29 - 14:20
June 28 - 04:53
July 27 - 20:21
August 26 - 11:57
September 25 - 02:53
October 24 - 16:46
November 23 - 05:40
December 22 - 17:49
January 8 - 22:26
February 7 - 15:54
March 9 - 11:20
April 8 - 07:18
May 8 - 02:09
June 6 - 18:32
July 6 - 07:51
August 4 - 18:19
September 3 - 02:38
October 2 - 09:46
October 31 - 16:41
November 30 - 00:19
December 29 - 09:35

2019 1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
January 6 - 01:29
February 4 - 21:04
March 6 - 16:05
April 5 - 08:51
May 4 - 22:46
June 3 - 10:02
July 2 - 19:17
August 1 - 03:13
August 30 - 10:38
September 28 - 18:27
October 28 - 03:39
November 26 - 15:06
December 26 - 05:14
January 14 - 06:46
February 12 - 22:27
March 14 - 10:28
April 12 - 19:06
May 12 - 01:13
June 10 - 06:00
July 9 - 10:55
August 7 - 17:31
September 6 - 03:11
October 5 - 16:48
November 4 - 10:24
December 4 - 06:59
January 21 - 05:17
February 19 - 15:54
March 21 - 01:43
April 19 - 11:13
May 18 - 21:12
June 17 - 08:31
July 16 - 21:39
August 15 - 12:30
September 14 - 04:33
October 13 - 21:08
November 12 - 13:35
December 12 - 05:13
January 27 - 21:11
February 26 - 11:28
March 28 - 04:10
April 26 - 22:19
May 26 - 16:34
June 25 - 09:47
July 25 - 01:19
August 23 - 14:57
September 22 - 02:41
October 21 - 12:40
November 19 - 21:12
December 19 - 04:58